By Maayan Lubell and Maya Gebeily

JERUSALEM/BEIRUT (Reuters) -Israel killed Hezbollah leader Sayyed Hassan Nasrallah in a powerful airstrike in Beirut, dealing a heavy blow to the Iran-backed group as it reels from an escalating campaign of Israeli attacks.

The Israeli military said on Saturday it had eliminated Nasrallah in the strike on the group’s central command headquarters in Beirut’s southern suburbs on Friday. Hezbollah confirmed he had been killed, without saying how.

Nasrallah’s death is a major blow to both Hezbollah and Iran, removing an influential ally who helped build Hezbollah into the linchpin of Tehran’s network of allied groups in the Arab world.

U.S. President Joe Biden described Nasrallah’s death as a measure of justice for what he called the Hezbollah chief’s many victims, including thousands of Americans, Israelis and Lebanese, and said the U.S. fully supported Israel’s right to self-defence.

A senior member of Iran’s Revolutionary Guards, deputy commander Abbas Nilforoushan, was also killed in the Israeli attacks in Beirut on Friday, Iranian media reported on Saturday.

Strikes continued on Beirut’s southern suburbs throughout the early evening on Saturday, according to a Reuters live broadcast, sending large clouds of smoke over the city.

The Israeli military said that in a strike on southern Beirut on Saturday it killed a senior member of Hezbollah’s intelligence, naming him as Hassan Khalil Yassin. Hezbollah made no mention so far of this.

In Israel, air raid sirens sounded across the centre of the country on Saturday – including Tel Aviv – and large bangs were heard after a missile was fired from Yemen and intercepted, according to the Israeli military.

Hezbollah said in a statement that it would continue its battle against Israel “in support of Gaza and Palestine, and in defence of Lebanon and its steadfast and honourable people”.

Lebanon’s caretaker Prime Minister Najib Mikati said his country was facing the threat of danger, without mentioning the death of Nasrallah. His office later announced three days of mourning for the Hezbollah chief.

Iran’s Supreme Leader Ayatollah Ali Khamenei said Nasrallah’s killing would be avenged and his path in fighting Israel would be continued by other militants.

Hezbollah and Israel have been fighting a conflict in parallel with Israel’s war against Palestinian group Hamas in Gaza since Hamas’ attack on southern Israel last Oct. 7, a conflict that has sharply escalated in recent days.

Hezbollah’s Al-Manar TV aired verses from the Koran after Nasrallah’s death was announced. Bursts of gunfire were heard in Beirut and Lebanon’s army deployed tanks in the city centre, according to Reuters witnesses.

Friday’s airstrike – a succession of massively powerful blasts that left a crater at least 20 metres (65 feet) deep – shook Beirut.

The Israeli military said Nasrallah was eliminated in a “targeted strike” on the group’s underground headquarters beneath a residential building in Dahiyeh – a Hezbollah-controlled southern suburb of Beirut.

It said he was killed along with another top Hezbollah leader, Ali Karaki, and other commanders.

“The strike was conducted while Hezbollah’s senior chain of command were operating from the headquarters and advancing terrorist activities against (Israeli) citizens”, it said.

Nasrallah’s death is by far the largest blow in a devastating fortnight for Hezbollah, starting with a deadly attack on thousands of wireless communications devices used by its members.

Days later, Israel significantly ramped up airstrikes in Lebanon, killing several top Hezbollah commanders and hundreds of other people across wide areas of the country.

SUCCESSION

Many Hezbollah supporters were in disbelief on Saturday.

“He was leading us. He was everything to us. We were under his wings,” one supporter, Zahraa, told Reuters tearfully by phone from a school where she had been displaced to overnight.

Hezbollah gave no immediate indication of who might succeed Nasrallah. Senior Hezbollah official Hashem Safieddine has long been regarded as heir apparent. The group has not issued any statement on Safieddine’s status or that of any other Hezbollah leaders – apart from Nasrallah – since the attack.

Hezbollah continued its cross-border rocket fire on Saturday, setting off sirens and sending residents running for shelter deep inside Israel. Israeli missile defences blocked some of them and there was no immediate report of injuries.

The escalation has increased fears the conflict could spin out of control, potentially drawing in Iran, Hezbollah’s principal backer, as well as the United States.

Israeli Defence Minister Yoav Gallant said Israel’s war was not with the Lebanese people, calling Nasrallah the “murderer of thousands of Israelis and foreign citizens”.

Hezbollah has been waging hostilities with Israel since the eruption of the Gaza war a year ago, when it opened fire declaring solidarity with its Palestinian ally Hamas.

Hezbollah has said it would cease fire only when Israel’s Gaza offensive ends. Hamas and other allies of Hezbollah issued statements mourning his death.

Russia said it strongly condemned Israel’s killing of Nasrallah and called on Israel to stop hostilities in Lebanon.

LEBANON ASKS IRANIAN PLANE NOT TO LAND

Residents fled Dahiyeh, seeking shelter in downtown Beirut and other parts of the city.

“Yesterday’s strikes were unbelievable. We had fled before and then went back to our homes, but then the bombing got more and more intense, so we came here, waiting for Netanyahu to stop the bombing,” said Dalal Daher, speaking near Beirut’s Martyrs Square, referring to Israeli Prime Minister Benjamin Netanyahu.

Israel says it has been attacking Hezbollah with the aim of allowing tens of thousands of residents evacuated from northern Israel to return home. In Lebanon, well over 200,000 people have been displaced, around half of them since Monday.

Lebanon’s transport ministry asked an Iranian plane not to enter Lebanese airspace after Israel warned air traffic control at the Beirut airport that it would use “force” if it landed, a ministry source told Reuters. The source said it was not clear what was on the plane, adding: “The priority is people”.

After cutting short his visit to New York, Netanyahu was due to hold a security consultation upon his arrival in Israel on Saturday, an Israeli official said.

Late on Friday, Israeli military spokesperson Rear Admiral Daniel Hagari said Israeli air force planes were “patrolling the area of the Beirut airport” and would not allow “hostile flights with weapons to land” there.

Iran Air has cancelled all flights to Beirut until further notice, the airline’s spokesman told local media on Saturday.

Hezbollah has fired hundreds of rockets and missiles at targets in Israel, including Tel Aviv, in recent weeks.