Israel?s military said the leader of Lebanese militant group Hezbollah was killed late Friday in an Israeli airstrike that targeted the group?s headquarters south of Beirut.

The Israel Defense Forces said in a statement Saturday that Hassan Nasrallah was "eliminated" in the airstrike along with Ali Karki, the commander of Hezbollah?s southern front and other Hezbollah commanders.

The statement said Israeli warplanes conducted the strike after the IDF received "precise intelligence" that senior Hezbollah leaders were inside the group?s central headquarters, which the IDF said was located under a residential building in Dahiyeh, a southern suburb of Beirut.

There was no immediate confirmation of Nasrallah?s reported death from Hezbollah officials.

Lebanon's Health Ministry said at least six people were killed and 91 were wounded in the Friday airstrikes. Lebanese television carried footage of the aftermath, with smoke rising from the flattened building and rubble filling the streets around it.

Meanwhile, a new wave of airstrikes hit suburbs south of Beirut and parts of southern Lebanon on Saturday as Israeli forces pressed on with attacks against Hezbollah.

Residents of Dahiyeh reported hearing jets and seeing more than a dozen explosions not long after Israel issued a warning for civilians to leave the area. Thousands fled their homes and camped in the streets as the fighting raged on.

In southern Lebanon, Israeli fighter jets struck targets in the Bekaa Valley. Israeli officials said the attacks targeted Hezbollah rocket launchers. Earlier, air raid sirens sounded in northern Israel and authorities said several projectiles had crossed from Lebanon into Israeli territory.

Israel?s military has mobilized more reserves as the fighting with Hezbollah escalates, amid speculation that Israel could launch a ground operation in Lebanon.

US: No involvement in airstrikes

Israeli sources said the U.S. had been notified moments before Friday?s airstrike, but Secretary of Defense Lloyd Austin said that the United States had no advance warning nor was it involved in the Israeli operation in Beirut.

"As you know, this operation took place just a few hours ago, and they're still making assessments, so I don't have any further information or specifics for you at this time," he said. "You've heard me say a number of times, an all-out war should be avoided."

IDF spokesperson Rear Admiral Daniel Hagari went on to say, after nearly a year of Hezbollah firing rockets and drone attacks into their country, "Israel is doing what every sovereign state in the world would do if they had a terror organization that seeks their destruction on their border."

The initial wave of Israeli strikes came about an hour after Israeli Prime Minister Benjamin Netanyahu finished addressing the United Nations General Assembly in New York. His office circulated a photograph of him on the telephone during the approval of the attack.

At the General Assembly, Netanyahu had a message for Iran, which sponsors both Hezbollah in Lebanon and Hamas in Gaza.

"If you strike us, we will strike you," he said. "There is no place ? there is no place ? in Iran that the long arm of Israel cannot reach. And that's true of the entire Middle East."

The U.N. secretary-general called for calm.

"We must avoid a regional war at all costs," Antonio Guterres said. He urged both Israel and Hezbollah to accept a 21-day cease-fire proposal put forward by the U.S. and France and backed by several countries.

"We need this cease-fire now," Guterres said. "We cannot afford endless negotiations, as we have on Gaza."

Prior to the airstrike on the Beirut suburb, Israel and Hezbollah had continued to exchange fire across Lebanon's southern border. Earlier Friday, at a news conference, acting Lebanese Health Minister Firass Abiad said Israeli airstrikes had continued overnight, killing 25 people and injuring an unspecified "large number" of others in the country.

Hezbollah fired rockets into the northern Israeli city of Tiberias, saying it was responding to "savage" strikes on Lebanese towns and villages. First responders in the city reported that three people suffered minor injuries.

In Geneva, U.N. humanitarian officials said the burgeoning conflict is having broader regional consequences.

The U.N. refugee agency's representative in Syria, Gonzalo Vargas Llosa, said more than 30,000 people have crossed the border from Lebanon into Syria in the past 72 hours due to the fighting. He said perhaps 75% to 80% of them are Syrians returning home. About 1.5 million Syrian refugees are in Lebanon, fleeing their own civil war.

The U.N. humanitarian coordinator in Lebanon, Imran Riza, told reporters, "We are witnessing the deadliest period in Lebanon in a generation, and many expressed their fear that this is just the beginning."

The U.N. on Friday released $10 million from its emergency humanitarian fund to help meet needs in Lebanon.(VOA, excluding headline)

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