Beirut | Hezbollah's acting leader vowed on Monday to continue battling Israel and said the militant group was prepared for a long fight even after much of its top command was wiped out, including its leader Hassan Nasrallah.

Israeli strikes have killed Nasrallah and six of his top commanders and officials in the last 10 days, and have hit what the military says are thousands of militant targets across large parts of Lebanon.

Over 1,000 people have been killed in Lebanon in the past two weeks, nearly a quarter of them women and children, according to the Health Ministry.

Early Monday, an airstrike hit a residential building, wiping out one apartment, damaging others, and killing three Palestinian militants in central Beirut, as Israel appeared to send a clear message that no part of Lebanon is out of bounds.

Despite the heavy blow Hezbollah has suffered in recent weeks, acting leader Naim Kassem said in a televised statement that if Israel decides to launch a ground offensive, the group's fighters are ready — noting that the commanders killed have already been replaced.

“Israel was not able to affect our (military) capabilities,” Kassem said in his first speech since Nasrallah was killed. “There are deputy commanders and there are replacements in case a commander is wounded in any post.” He added that Hezbollah anticipated “the battle could be long”.

A founding member of Hezbollah who had been Nasrallah's longtime deputy, Kassem will remain in his acting position until the group's leadership elects a replacement. The man widely expected to take over the top post is Hashem Safieddine, a cousin of Nasrallah who oversees the group's political affairs.

Hezbollah has significantly increased its rocket attacks in the past week to several hundred daily, but most have been intercepted or fallen in open areas. Several people have been wounded in Israel. There have been no fatalities since two soldiers were killed near the border on September 19.

But Hezbollah's capabilities remain unclear.

As recently as two weeks ago, a strike like Monday's in central Beirut — outside of the main areas where Hezbollah operates and next to a busy transportation hub normally crowded with buses, taxis and vans — would have been seen as a major escalation and likely followed by a long-range Hezbollah strike into Israel.

But the unspoken rules of the long-running conflict are no longer clear.

It's possible that Hezbollah is holding back to save resources for a bigger battle, including a threatened Israeli ground invasion. But the militant group might also be in disarray after Israeli intelligence apparently penetrated its highest levels.

In the past week, Israel has frequently targeted Beirut's southern suburbs, where Hezbollah has a strong presence — including the massive strike on Friday that killed Nasrallah — but had not hit locations closer to the city centre.

The strike early Monday killed three members of the Popular Front for the Liberation of Palestine, a small, leftist faction that has not been meaningfully involved in months of fighting between Israel and Hezbollah in Lebanon. Israel has not claimed the strike but is widely assumed to have carried it out.

Also on Monday, Hamas announced that its top commander in Lebanon, Fatah Sharif, was killed with his family in an airstrike on the Al-Buss refugee camp in the southern port city of Tyre. The Israeli military confirmed that it had targeted him.

Hezbollah began firing rockets, drones and missiles into northern Israel after Hamas' October 7 attack from Gaza into Israel sparked the war there. Hezbollah and Hamas are allies and both supported by Iran, and Hezbollah said it would continue the attacks in solidarity with the Palestinians until there was a cease-fire in Gaza.

Israel has responded to the rockets with airstrikes in Lebanon, where Hezbollah is based, and the fighting has steadily escalated over the past year. The Lebanese government says the fighting may have displaced up to a million people, although the UN estimate is around 200,000.

Tens of thousands of Israelis have also been displaced. Israel has vowed to keep fighting until the attacks stop and its citizens can return to their homes.

The United States and its allies have called for a cease-fire, hoping to avoid further escalation that could draw in Iran and set off a wider war. But Israeli Prime Minister Benjamin Netanyahu has shown little interest, as his country racks up military achievements against a longtime foe.

Some Israelis broke into spontaneous celebrations after Nasrallah's death was announced. Videos circulated of crowds at bars singing a song in Hebrew mocking him. A news anchor on a pro-Netanyahu station sang and danced as the studio audience joined in with him while a commentator on Israel's largest TV station offered co-panelists celebratory shots.

Hezbollah, which boasts tens of thousands of battle-hardened fighters and long-range missiles capable of hitting anywhere inside Israel, has long been seen as the most powerful militant group in the region and a key partner to Iran in both threatening and deterring Israel.

Hezbollah fought Israel to a month-long stalemate in their 2006 war, But Hezbollah has never faced an onslaught quite like this one, which began with a sophisticated attack on its pagers and walkie-talkies in mid-September that killed dozens of people and wounded around 3,000 — including many fighters but also many civilians.

White House national security spokesman John Kirby said Israel's airstrikes in Lebanon had “wiped out” Hezbollah's command structure but warned that the group will work quickly to rebuild it.

“We're watching to see what they do to try to fill this leadership vacuum. It's going to be tough,” he told CNN's “State of the Union” on Sunday.