The strike set off huge explosions and left a ruined landscape of jagged concrete, twisted metal and smoldering debris in the Dahiya, a densely populated area where an Israeli strike on Sept. 28 killed Hezbollah’s longtime leader, Hassan Nasrallah.

Above is a look at who has been killed and targeted among Hezbollah’s leadership.

“Our family and the entire camp is already devastated,” said Anas Kharyoush, a cousin of the children’s mother, 28-year-old Saja Abu Zahra, referring to the neighborhood’s origin as a refugee camp for Palestinians displaced from their homes by the wars surrounding Israel’s establishment. “They are not the first martyrs in our family, and this is not the first airstrike in our neighborhood, but it’s the most devastating.”

The explosion was so fierce that the remains of those killed had to be gathered in blankets and sheets and taken to a hospital for bereft family members to identify, according to residents and videos of the aftermath. And the search for the missing continued.

“Mothers are desperate to know about their children, and families are still looking for their loved ones,” said Diala Hadaydah, a paramedic who lives in the neighborhood, who rushed to the scene moments after the strike.

The Israeli military did not respond to questions about the number of civilians killed in Thursday’s strike.

The strike in the densely packed area came amid increasingly deadly Israeli raids on Palestinian towns and cities across the Israeli-occupied West Bank, in what the military labels counterterrorism operations.

Tulkarm, which has a history of armed resistance against the nearly six-decade Israeli occupation of the West Bank, has been the frequent target of such raids. For more than nine days, starting in late August, Israeli bulldozers ripped through roads, infrastructure and businesses there, as well as in nearby Jenin.

Palestinians say they are terrified in their own homes, fearful of onslaughts from the ground — from tanks, armored vehicles or more bulldozers — and from the sky. The Israeli military has said the raids are an effort to crack down on Palestinian armed groups and combat rising attacks against Israelis and settlements.

Israeli settlements are considered illegal under international law but have continued to expand, threatening Palestinian livelihoods in cities, towns and farming villages.

Violence in the West Bank has been increasing since the war began in Gaza last Oct. 7, but the toll has been far higher among Palestinians. As one gauge, a United Nations report in mid-September, counting conflict fatalities from January 2023 onward, put Israeli fatalities at 41 and Palestinian fatalities at 722.

In the strike on Tulkarm on Thursday, witnesses said that an Israeli warplane fired at least one missile at the cafe while it was occupied by civilians. The use of a warplane there was unusual. Though Israel has increasingly been conducting once-rare airstrikes in the West Bank since the Oct. 7 Hamas-led attack on Israel, they have usually been carried out by armed drones.

Ms. Hadaydah, the paramedic, said the sound of the explosion was unlike anything she had ever heard before. She rushed to the scene and saw the scattered remains of body parts, burned beyond recognition. Ms. Hadaydah said only five bodies were intact.

“I saw teeth, I saw skin, I saw bodies hanging from electricity cables,” Ms. Hadaydah said. “It looked just like Gaza”

Ayatollah Khamenei switched to speaking in Arabic to address Palestinians and the people of Lebanon, which has been battered by Israeli strikes targeting Hezbollah, and said that Iran shared an enemy with them, referring to Israel. He also defended Tuesday’s Iranian missile attack against Israel as “completely legal and legitimate.”

“What our armed forces did was the least punishment they could do” against Israel, he said, adding that “what is logical and rational will be done at the right time and will be done again in the future if necessary.”

On Tuesday, Iran fired nearly 200 missiles at Israel in retaliation for Mr. Nasrallah’s death, as well as for the recent killings of Hamas’s political leader, Ismail Haniyeh, and an Iranian commander, Iran’s Islamic Revolutionary Guards Corps said.

In a series of attacks, Israel has been diminishing the military abilities of and dismantling the leadership of Hezbollah, a militia group backed by Iran and based in Lebanon. On Thursday night around midnight, Israel launched an intense barrage of airstrikes in a neighborhood south of Beirut in an effort to target Hashem Safieddine, Mr. Nasrallah’s presumed successor, according to three Israeli officials.

It is rare for Ayatollah Khamenei to lead Friday Prayer and deliver the sermon, typically doing so under extraordinary circumstances related to Iran’s national security. The last time was in 2020 after the United States killed Iran’s top general, Maj. Gen. Qassim Suleimani, in Iraq. Iran retaliated by firing ballistic missiles at an American base in Iraq.

Ayatollah Khamenei’s appearance in person, despite security concerns, signaled the significance of the moment as anxiety mounts that Israel and Iran appear prepared to risk direct conflict.

Large crowds of men and women waited in lines on Friday that began forming outside the compound as early as 6 a.m., several hours before the event started, videos published by Iranian news media showed.

Ayatollah Khamenei said earlier in the week in televised comments that he was in mourning for Mr. Nasrallah, but that the grief would fuel Iran’s resolve to fight Israel.

Plans for an official funeral for Mr. Nasrallah have not been announced. It is not clear whether it is feasible for Hezbollah and what remains of its leadership to gather publicly, given Israel’s attacks.

Israel said on Friday that a separate airstrike the previous day had killed Mohammad Rashid Sakafi, who it identified as a commander responsible for Hezbollah’s telecommunications division. Hezbollah, the Lebanese militia and political party backed by Iran, did not immediately comment on the claim.

As Israeli warplanes pummeled the Beirut area, soldiers were waging a ground invasion in southern Lebanon targeting what military officials said were Hezbollah sites in the rugged border area.

New evacuation orders issued on Friday brought to 87 the total number of Lebanese communities whose residents Israel has told to leave. Many are to the north of a swath of southern Lebanon that was designated a buffer zone by a 2006 U.N. Security Council resolution after the last Israel-Hezbollah war.

Israeli fighter jets also struck near of Lebanon’s Masnaa border crossing with Syria, cutting off a road used by hundreds of thousands of people fleeing Lebanon, Bachir Khodr, the governor of the Baalbek-Hermel region, said on Friday.

The Israeli military said the area — which lies on the highway linking Beirut and Damascus near the geographic center of the country — also contained a two-mile-long tunnel that was the main route used by Hezbollah to bring weapons into Lebanon from Syria, another Iranian ally.

The Israeli airstrike left a crater in the road but people were still crossing into Syria on foot, Rula Amin, a spokeswoman for the U.N. refugee agency, told reporters by video link from Beirut on Friday. “It’s a testament to the fear and panic that is driving people to cross into Syria,” she said.

In Israel on Friday, air-raid sirens sounded across much of the north as Hezbollah continued to fire rockets at the region. Residents reported hearing loud explosions in the sky — possibly from air defenses intercepting rockets. Israel’s military said around 100 rockets had been launched as of early afternoon, but the authorities did not immediately report casualties or significant damage.

Euan Ward contributed reporting from Beirut, Lebanon, and Nick Cumming-Bruce from Geneva.

“Nobody I know has prepared for a possible war,” Mahdieh, 41, an engineer in Tehran, said in a phone interview. “We are jarred. Let us have our normal life. We are not willing or want to enter a war era.” She asked that her last name not be published out of fear of retribution. She said she and her husband had prepared an emergency bag with their documents in case they needed to leave Tehran.

A message shared widely on social media by many Iranians read, “NO WAR,” and “Which bunkers will you use to shield the people? How will you repair damaged infrastructure? There is no good in war, do not lay ruin to Iran.”

On Monday Iran launched 180 ballistic missiles into Israel in retaliation for Israel’s killing of its top regional ally, the Hezbollah leader, Hassan Nasrallah, that of a senior Iranian general in Beirut and that of the political leader of Hamas in Tehran. Israel has said it plans to respond by attacking Iran; its potential targets include military bases for the Revolutionary Guards Corps and oil refineries.

President Masoud Pezeshkian of Iran traveled to Qatar on Wednesday to attend a conference of the Organization of Islamic Countries, where he said that Iran did not seek war, saying “there are no winners in war, we know this.” And then he warned, “Iran will respond stronger if Israel makes the slightest mistake.”

Iran’s mission to the United Nations said in a statement that Tehran and Washington had exchanged messages through their official intermediary in Tehran in the aftermath of the attack on Israel. The statement said that Iran considered any country that assisted Israel in an attack on Iran “an accomplice and a legitimate target.”

According to two Iranian officials, who are familiar with the war planning and were not authorized to speak publicly, Iran had asked Russia for cooperation with satellite intelligence ahead of an Israeli strike.

But despite the official saber rattling, even some supporters of the government who had cheered the attacks on Israel were now confronting the realities of an all-out war that could take out infrastructure and harm the economy. Facing that possibility, some said they hoped Israel’s response would be limited and any tit-for-tat strikes would end quickly.

“We had to slap it [Israel] in the face, otherwise it would keep moving forward,” Hamidreza Jalaeipour, a prominent sociologist close to the reformist faction, said in a discussion on the application Clubhouse. “If there is a war, it will be imposed on us.”

Mr. Jalaeipour said he predicted that in the event of war the majority of Iranians would rally behind the flag to defend their country forcefully and put divisions aside.

But discontent against the government runs deep, and in waves of protests, notably in the women-led uprising in 2022, demonstrators called for the toppling of the ruling clerics. The loyalty and ideological fervor of the early years of the revolution — when even teenagers volunteered for the front lines of the eight-year war the country was then fighting with Iraq — has given way to despair and frustration with the status quo.

Some opponents of the government said they were angry that Iran had struck Israel in the first place, placing the lives and safety of its own citizens at risk for a cause outside its own borders. In anti-government protests in previous years, people have chanted, “No to Gaza, no to Lebanon, my life for Iran.”

And now that Israeli attacks seemed likely and imminent, the government had not announced any emergency provisions to prepare the population for war.

“Most of us are not happy about the interference of the Islamic Republic in the region and its so-called proxies. People do not want their national resources to be spent abroad,” said Mahan, a 50-year-old doctor in the northern city of Rasht. “The most pressing feeling these days, both for myself and the majority of friends and people I know, is the fear and worry of war.”

He said that she had endured significant trauma over a long period, including rape and abuse. She received food and basic treatment in Israel, he said, and U.S. officials then escorted her to Jordan by car, from which she was returned to her family in Iraq. An Israeli diplomat, David Saranga, posted a video on social media showing Ms. Sido’s return, and said her captor was “a Palestinian Hamas-ISIS member.” The New York Times has not verified the video.

Ms. Sido and her family could not be contacted for comment.

General Goren said that the Israeli military had learned about her situation based on intelligence, and that the Israeli authorities engaged the United States for more information. Israel and the United States then began planning the operation, which added the cooperation of Jordan, and other unnamed international partners, he said.

Ms. Sido was sold by an ISIS operative more than 10 years ago to a member of Hamas who took her to the Gaza Strip, possibly through the Rafah crossing at the Egyptian border, General Goren said. That timing suggests she was initially captured when ISIS overran northern Iraq in 2014 and carried out what the United Nations has deemed a genocide against the Yazidi, an ethno-religious minority.

Her captor in Gaza was killed, General Goren said, most likely by an Israeli airstrike, and Ms. Sido fled and hid. He did not specify when that occurred, but said that it was at that point that the Israeli authorities learned of her existence, confirmed it with Americans and planned the rescue operation. She was taken out of Gaza through the Kerem Shalom crossing, another entry point at Gaza’s southern border.

The Yazidis were targeted by the Islamic State, or ISIS, in August 2014, when ISIS captured about one-third of northern Iraq and large areas of territory in neighboring Syria. Up to 10,000 Yazidis were killed; about 400,000 were displaced from their homes in Iraq’s remote, mountainous Sinjar district; and more than 6,000 were enslaved, most of them women and children, according to Yazda, a nonprofit group created in the wake of the onslaught to aid Yazidis.

Many of the enslaved Yazidis were sold in slave markets in Syrian cities, according to the Norwegian Refugee Council, a humanitarian agency.

In 2015, Sinjar was captured from ISIS by Kurdish forces and Yazidi fighters with the backing of American air power.

Rawan Sheikh Ahmad contributed reporting.

The attempted assassination was the latest move by Israel in its quest to steadily decapitate much of Hezbollah’s leadership. It followed Israel’s invasion of southern Lebanon earlier this week.

Mr. Safieddine, born in the early 1960s in southern Lebanon, was one of Hezbollah’s earliest members. He joined after the Shiite Muslim group was formed in the 1980s, with Iranian guidance, during Lebanon’s long civil war. He rose quickly up its ranks alongside Mr. Nasrallah, playing many roles and serving as a political, spiritual and cultural leader, as well as leading the group’s military activities at one point.

As Mr. Nasrallah did, Mr. Safeiddine usually appeared in a black turban, marking him as a revered Shiite cleric who could trace his ancestry back to the Prophet Muhammad.

Biographical information reported in various outlets across the Middle East and Turkey portrays a rapid rise through Hezbhollah’s ranks. In 1995, he was promoted to Hezbollah’s highest council, its governing Consultative Assembly, and was soon after appointed as head of the group’s Jihadi Council, which controls Hezbollah’s military activities. Just three years later, in 1998, Mr. Safieddine, was elected to lead the party’s Executive Council, a position that was also twice held by Mr. Nasrallah, including before his appointment as Hezbollah’s secretary-general in 1992, the report said.

Like Mr. Nasrallah, he studied in Iran. Mr. Safieddine formed strong ties with Tehran during his religious studies in the Iranian city of Qom before returning to Lebanon to work for Hezbollah.

Those ties are also deeply personal. He was close friends of Maj. Gen. Qassim Suleimani, an Iranian who commanded the Islamic Revolutionary Guards Corps’ Quds Force until the United States killed him in an airstrike in Baghdad in 2020.

Later that year, Mr. Safieddine’s son Reza Hashem Safieddine married the Iranian general’s daughter, Zeinab Suleimani, in a much-publicized wedding. The marriage was seen by some analysts and critics as emblematic of Iran’s entrenchment in Hezbollah. The U.S. Treasury Department has described Mr. Safieddine’s brother, Abdallah Safieddine, as Hezbollah’s representative to Iran.

Mr. Safieddine was designated a terrorist by the United States and Saudi Arabia in May 2017 for his leadership role in Hezbollah. At the time, the State Department called him “a senior leader” in Hezbollah’s Executive Council, which oversees the group’s “political, organizational, social, and educational activities.” It said that Mr. Safieddine posed “a serious risk of committing acts of terrorism that threaten the national security and foreign policy of the United States.”

The United States designated Hezbollah a terrorist organization in 1997 and holds the group responsible for multiple attacks that killed hundreds of Americans, including the suicide truck bombings of the U.S. Embassy and U.S. Marine barracks in Beirut in 1983, the U.S. Embassy annex in Beirut in 1984 and the 1985 hijacking of TWA flight 847.

Farnaz Fassihi contributed reporting.

The strike was a sign that Israel had not let up on its campaign to eliminate the leadership of the Iranian-backed group, nearly a week after Mr. Nasrallah was killed.

Mr. Safieddine, Mr. Nasrallah’s cousin, is in his 50s and has long been a major player in Hezbollah and has been considered a contender to become the group’s new secretary general. Israeli officials previously told The New York Times that Mr. Safieddine was one of the few senior Hezbollah leaders not present at the site of Israel’s heavy bombardment last Friday near Beirut that killed Mr. Nasrallah.

It was not immediately clear if Mr. Safieddine was present in the bunker struck overnight Friday.

The Israeli military did not immediately respond to a request for comment about the strike, but had issued an evacuation order for the Burj al-Barajneh neighborhood in southern Beirut late on Thursday night. Shortly afterward, around midnight, a series of huge explosions rocked the Dahiya, the densely populated neighborhoods just south of Beirut where Mr. Nasrallah was killed and Hezbollah holds sway.

The shock waves sounded across the Lebanese capital, shaking buildings; they were felt at least 15 miles away. It was one of the heaviest bombardments in the area since the war began last October, according to Lebanon’s state-run news agency.

Who is Hashem Safieddine?

Born in the early 1960s in southern Lebanon, Mr. Safieddine was one of Hezbollah’s earliest members after the Shiite Muslim group was formed in the 1980s, with Iranian guidance, during Lebanon’s long civil war.

He rose quickly up its ranks alongside Mr. Nasrallah, playing many roles and serving as a political, spiritual and cultural leader, as well as leading the group’s military activities.

Mr. Safieddine has strong ties with Tehran, formed during his religious studies in the Iranian city of Qom. Like Mr. Nasrallah, he studied in Iran before returning to Lebanon to work for Hezbollah.

A cleric, Mr. Safieddine was designated a terrorist by the United States and Saudi Arabia in May 2017 for his leadership role in Hezbollah. At the time, the State Department called him “a senior leader” in Hezbollah’s executive council, which oversees the group’s political, organizational, social and educational activities.

Which other Hezbollah leaders has Israel targeted?

The strike targeting Mr. Safieddine was the latest in a series of successful Israeli attacks in Lebanon seeking to kill Hezbollah’s leaders.

On Thursday, an Israeli strike targeted the Hezbollah commander Rashid Shafti, the group’s official in charge of telecommunications and computer division in Beirut, according to two Israeli officials. Mr. Shafti had lost fingers in the wave of electronic explosion attacks Israel carried out this month, they added.

The Israel Defense Forces said in a statement on Thursday that it had also killed Mahmoud Yusef Anisi, a Hezbollah official it said had been involved in the group’s precision-guided missile manufacturing chain in Lebanon.

In the strike that killed Mr. Nasrallah last week, several of the group’s leaders were also slain, including Ali Karaki, Hezbollah’s top commander in southern Lebanon.

Ibrahim Aqeel, who oversaw Hezbollah’s military operations and founded the group’s elite commando unit, was killed on Sept. 20.

Euan Ward contributed to reporting.

The Israeli military said in a statement early Thursday that it had killed the head of Hamas in Tulkarm, Zahi Yaser Abd al-Razeq Oufi, “alongside additional terrorists.” It said he had planned and led multiple “significant” shooting attacks and car bombings on Israeli civilians in the West Bank and had supplied weapons to other operatives who also carried out attacks on Israelis.

The Israeli airstrike was aimed at a popular cafe in Tulkarm, according to Wafa news agency, killing a family in an adjacent house and children and older people in the neighborhood.

Tulkarm has been the focus of recent Israeli military raids in the West Bank, which have destroyed the city’s infrastructure and businesses.

Suleiman Zuhairi, a former Palestinian deputy minister who lives on the outskirts of Tulkarm, said Israel had not carried out such a bombardment in the West Bank for years, if not decades.

“The blast was terrifying,” he said. “My house trembled from the shock wave,” he continued, though it was a distance from the reported blast site.

Mr. Zuhairi said that with Israel’s assault on Lebanon drawing international attention, and its continuing war in Gaza doing so to a lesser extent, Israel was operating with a free hand to escalate its campaign in the West Bank.

Aaron Boxerman reported from Jerusalem, and Ephrat Livni from New York.

Oil prices rose more than 4 percent on Thursday, with Brent crude, the global benchmark, climbing above $77 a barrel for the first time in a month after Mr. Biden’s remarks. Before the missile attack, Brent was trading at just above $71 a barrel.

Prime Minister Benjamin Netanyahu of Israel said after Iran’s attack on Tuesday that Tehran had “made a big mistake — and it will pay for it.”

When asked if he would allow Israel to retaliate against Iran, which said it had launched the missiles in retaliation for the assassinations of leaders of Hamas and Hezbollah, its proxies, Mr. Biden said: “First of all, we don’t ‘allow’ Israel. We advise Israel. And there is nothing going to happen today.”

Iran is a major oil producer, pumping about two million barrels a day, or about 2 percent of the world’s supply. Its production and sales are hampered by international sanctions, and most of its exports are bought by China.

The intensifying fighting between Israel and Iran and Iranian-backed groups, especially Hezbollah in Lebanon, has pushed up oil prices this week. The main concern is that the escalating conflict could prompt Tehran to try to restrict the flow of oil from key exporters like Saudi Arabia and the United Arab Emirates.

Prices haven’t climbed back to their peaks this year, however, because those worries have been largely outweighed by factors like weak energy demand in China and increased oil production in the United States and elsewhere.

An agreement reached in June by Saudi Arabia and seven other oil producers to begin unwinding some production cuts also continues to weigh on prices. While these increases were recently postponed, the anticipation of increased supplies coming onto the market has offset some of the worry about potential outages stemming from fighting between Iran and Israel.

Until recently, oil prices had been steadily drifting lower, down from about $90 a barrel six months ago.