An Israeli airstrike that targeted Hezbollah commanders in a Beirut suburb on Friday killed at least 37 people, including three children and seven women, the Lebanese health ministry said, as rescuers continue to search on Saturday for people missing in the rubble.

Hezbollah said overnight that 16 of its members including senior leader Ibrahim Aqil and another top commander, Ahmed Wahbi, were among those killed in the deadliest strike in nearly a year of conflict between Israel and the Iran-backed group.

The Israeli army, in posts on X, said the strike hit an underground gathering of Aqil and senior commanders of Hezbollah's elite Radwan forces, and had "almost completely dismantled" Hezbollah's military chain of command.

The attack leveled a multistory residential building in the crowded suburb and a nursery next door was damaged, a security source said.

Heavy cross-border strikes continued on Saturday, with Israeli warplanes carrying out some of the heaviest bombings in 11 months of fighting across Lebanon's south and Hezbollah claiming rocket attacks on military targets in Israel's north.

The Israeli army said it hit around 180 targets, destroying thousands of rocket launch barrels.

Friday's strike sharply escalated the conflict between Israel and Hezbollah, and inflicted another blow on Hezbollah after two days of attacks this week in which pagers and walkie-talkies used by its members exploded.

The total death toll in those attacks has risen to 39, and more than 3,000 were injured.

The attacks on communications devices were widely believed to have been carried out by Israel, which has neither confirmed nor denied its involvement.

Lebanese Prime Minister Najib Mikati canceled a planned trip to the United Nations General Assembly in New York over the escalating conflict, his office said in a statement.

U.S. national security adviser Jake Sullivan said he was worried about an escalation between Israel and Lebanon but that the Israeli killing of a top Hezbollah leader may lead to a cease-fire with the group, which Washington designates as a terrorist group.

"While the risk of escalation is real, we actually believe there is also a distinct avenue to getting to a cessation of hostilities and a durable solution that makes people on both sides of the border feel secure," Sullivan told reporters Saturday.

Hezbollah has said it will keep fighting Israel until it agrees to a cease-fire in its war against Hamas in the Palestinian enclave of Gaza. The war was triggered by a Hamas-led rampage in southern Israel on October 7.

Hamas militants killed about 1,200 people and captured about 250 hostages. Israel believes Hamas is still holding about 100 hostages, the military believes about a third are dead. Israel’s counteroffensive in Gaza has killed more than 41,000 Palestinians, according to the territory's health ministry, which does not distinguish between combatants and civilians in its count. Israel hasn’t estimated the death toll recently but says that most of the dead are combatants.

U.S. officials say a truce is unlikely to come anytime soon. Israel wants Hezbollah to cease fire and withdraw its forces from the border region irrespective of any Gaza deal.

Hezbollah said overnight that 15 more of its members were killed, including senior commander Wahbi, who oversaw the military operations of the Radwan forces during the Gaza war until early 2024.

In a brief statement on Friday evening, Israeli Prime Minister Benjamin Netanyahu said Israel's goals were clear and its actions spoke for themselves.

Defense Minister Yoav Gallant, who said this week Israel was launching a new phase of war on the northern border, posted on X: "The sequence of actions in the new phase will continue until our goal is achieved: the safe return of the residents of the north to their homes."

Tens of thousands of people have left their homes on both sides of the Israel-Lebanon border since Hezbollah began firing rockets at Israel in October in sympathy with Palestinians in Gaza.

Israel's military said on Saturday that airspace in northern Israel — from the city of Hadera north — was closed to private flights, but that the measure did not affect international flights.

With at least 70 people killed in Lebanon this week, the death toll in the country since October has surpassed 740. The current conflict between Israel and Hezbollah is the worst since they fought an all-out war in 2006.

While the current conflict has largely been contained to areas at or near the frontier, this week's escalation has heightened concerns that it could widen and further intensify.