Israel carried out a deadly air raid Thursday on a Hezbollah rescue facility in central Beirut, Lebanese sources said, after multiple Israeli ground troops were killed near the border.

The second strike targeting the capital's center this week follows Iran launching its largest missile attack yet on its arch-foe Israel, prompting Prime Minister Benjamin Netanyahu to warn Tehran would pay for its "big mistake".

Iran, which backs Hezbollah, said it would step up its response if Israel retaliates, defying calls for de-escalation in a war that has cost more than 1,000 lives in Lebanon.

The latest Israeli strike hit a Hezbollah rescue facility, a source close to the group told AFP, killing at least six people, according to a Lebanese health ministry toll.

AFP journalists in Beirut heard a loud explosion and reported some buildings shaking.

Israel, shifting its focus from the Gaza war sparked by Hamas's October 7 attack, says it is trying to secure its border with Lebanon so tens of thousands of Israelis displaced by nearly a year of exchanges of fire with Hezbollah can return home.

Israel has bombarded Hezbollah's south Beirut stronghold, having dealt a significant blow to the group last week by killing its leader, Hassan Nasrallah, in a massive strike.

A day after its military said it was conducting "targeted ground raids" in south Lebanon, Israel reported the first death of a soldier in the Israel-Hezbollah war, a toll that later rose to eight dead.

Hezbollah said it forced Israeli soldiers to retreat, targeted an Israeli unit with explosives, and destroyed three Merkava tanks with rockets as they advanced on Maroun al-Ras village.

The Israeli military said it staged two brief incursions into Lebanon, ordering residents to flee more than 20 areas.

The military released footage that it said showed soldiers inside Lebanon, moving through villages and mountainous areas on foot, and announced it had deployed a second division to support the fighting.

Israel launched three air raids on Beirut's southern suburbs just before midnight Wednesday, a source close to Hezbollah said, the third wave of strikes in the past 24 hours. The explosions were audible kilometres away.

Residents in multiple parts of densely-populated southern Beirut were told by the Israeli military to leave the area in the early hours of Thursday, in an order published on social media.

Lebanon's health ministry said 46 people were killed and 85 others injured by Israeli strikes over the past 24 hours.

Earlier, Lebanon's disaster management agency said 1,928 people have been killed in Lebanon since Israel and Hezbollah began trading cross-border fire after the Gaza war erupted nearly a year ago.

Iran missile attack

The Syrian Observatory for Human Rights, a Britain-based war monitor, said an Israeli strike in Damascus killed four people including Hassan Jaafar al-Qasir, son-in-law of the slain Hezbollah leader.

The Britain-based war monitor said one of them was Hassan Jaafar al-Qasir, son-in-law of the slain Hezbollah leader.

Hours after Israel announced the start of ground operations in Lebanon, Iran fired some 200 missiles including hypersonic weapons, sending frightened Israeli civilians into shelters.

Israel said it intercepted most of them. Two people were wounded by shrapnel and a school building was damaged.

The Israeli military said several Iranian missiles struck inside air force bases without causing any casualties or damage.

In Jericho in the occupied West Bank, a Palestinian was killed when "pieces of a rocket fell from the sky and hit him", the city's governor Hussein Hamayel said.

Israeli Defence Minister Yoav Gallant warned that "those who attack the state of Israel, pay a heavy price."

President Joe Biden said the US was "fully supportive" of Israel, but ruled out supporting its ally with a strike on Iran's nuclear sites.

Iran's armed forces chief of staff, Major General Mohammad Bagheri, threatened to fire "with bigger intensity" if Israel makes good on its pledge to retaliate.

Iranian President Masoud Pezeshkian also warned of a "stronger" response, though he stressed Iran was "not looking for war".

Iran's Revolutionary Guards said the missiles were fired in retaliation for Nasrallah's killing alongside its Quds Force commander Abbas Nilforoushan, as well as Hamas leader Ismail Haniyeh in a Tehran bombing in July.

Global alarm

In Israel's commercial hub Tel Aviv, resident Liron Yori said he felt "very, very disappointed".

"I see where the war's going and I don't feel comfortable with it," the 22-year-old told AFP.

In central Beirut, people were weary and afraid, though some Hezbollah supporters were defiant.

Youssef Amir, displaced from southern Lebanon, said: "I have lost my home and relatives in this war, but all of that is a sacrifice for Lebanon, for Hezbollah".

Iran's missile attack, its second on Israel in six months, triggered widespread global alarm, as well as a spike in world oil prices.

UN chief Antonio Guterres condemned the Iranian attack on Israel, saying they "do nothing to support the cause of the Palestinian people".

The G7 group of rich nations vowed to work together to reduce tensions in the region and said a diplomatic solution was "still possible".

Hezbollah began low-intensity strikes on Israeli troops a day after Hamas staged its October 7 attack on Israel, which resulted in the deaths of 1,205 people in Israel, mostly civilians, according to an AFP tally based on Israeli official figures that include hostages killed in captivity.

Israel's retaliatory military offensive has killed at least 41,689 people in Gaza, the majority of them civilians, according to figures provided by the Hamas-run territory's health ministry. The UN has described the figures as reliable.

In Gaza, the health ministry said its toll published Wednesday includes 51 deaths over the past 24 hours.

© Agence France-Presse By Lisa Golden with David Stout in Jerusalem