Twenty-two people have been killed and 117 injured in Israeli air strikes on central Beirut, Lebanon's Health Ministry said.
BBC reporters heard loud explosions echoing from the site of a strike in Bachoura, a small Shia area in the Lebanese capital. Rescuers were seen digging through rubble at the scene.
Ambulances rushed many injured to the American University hospital.
Unconfirmed media reports suggested the apparent target was Wafiq Safa, Hassan Nasrallah's brother-in-law and one of Hezbollah's high-ranking security officials. The group's media office has not yet commented.
The Beirut strikes came after two relatively calm days in Lebanon’s capital, which has felt unusual after intensive strikes in recent weeks.
There was no warning beforehand.
This is the third time Israel has launched air strikes on the city outside of the suburb of Dahieh, where it has struck repeatedly, killing Hezbollah commanders and destroying munitions caches.
One woman outside the hospital, who did not want to be named, said she was in the building next-door to the blast and heard the explosion.
She said the building which was hit was entirely residential, adding that it was about four or five floors high. One of her relatives was being treated for head injuries.
The Beirut attack came hours after two Indonesian peacekeepers were injured in southern Lebanon when an Israeli tank fired at a watchtower, according to the UN.
An observation tower at a UN base in Naqoura was directly hit, causing the peacekeepers to fall, the United Nations Interim Force in Lebanon (Unifil) said in a statement.
Unifil is a UN peacekeeping mission created in 1978, monitoring hostilities and helping to ensure humanitarian access to civilians in southern Lebanon.
The UN said Israeli forces had "repeatedly hit" UN positions in the last 24 hours. Israeli soldiers are also accused of deliberately shooting at the cameras and lights at two other Unifil bases.
The IDF said its troops had fired from the area around the base after ordering members of the base to remain in "protected places".
Both peacekeepers were not seriously injured but remain in hospital, the UN said, adding that deliberate attacks on its peacekeepers were a "grave violation of international law".
In a separate incident, Israeli soldiers fired at a base in Naqoura, "hitting the entrance to the bunker where peacekeepers were sheltering, and damaging vehicles and a communications system," the UN added.
An Israeli drone was also spotted flying above the bunker entrance.
Also in Naqoura, Hezbollah said it fired rockets at Israeli soldiers on the ground and used guided missiles to destroy a tank heading towards the area, leading to casualties.
There are now four divisions of Israeli soldiers fighting inside Lebanon as it continues its ground operations against Hezbollah, launched on 30 September.
A spokesperson for Unifil told the BBC on Thursday the force was "alarmed" and "deeply concerned" by the Israeli army's activity in the area where peacekeeping troops are based.
Positions hit by Israeli forces are well known as UN sites, Andrea Tenenti said, adding it would be important to have a discussion with Israeli authorities "to understand what happened".
Since 1978, Unifil has been operating in southern Lebanon, between the so-called "Blue Line" - the unofficial boundary separating Lebanon from Israel and the Israeli-occupied Golan Heights - and the Litani river, about 30km (20 miles) to the north.
Last week, Unifil refused to leave its positions near the Blue Line after being ordered to do so by the IDF.
There are around 10,000 Unifil military peacekeepers in Lebanon, from 50 contributing countries. There are also about 800 civilian staff.
Indonesia, where the injured peacekeepers are from, supplies more than 1,200 troops to Unifil, more than any other country.
The defence minister in Italy, which contributes more than 1,000 troops to Unifil, said the incidents were "intolerable" and must be "carefully and decisively avoided".
Around 190 rockets were fired from Lebanon into Israel by Hezbollah on Thursday, the Israeli military said.
Earlier on Thursday, the Lebanese ministry of public health said an Israeli air strike on the village of Karak in eastern Lebanon had killed four people, injuring 17.
Lebanon’s government says as many as 1.2 million people have fled their homes over the past year.
Hostilities in the region have escalated steadily since Hezbollah began firing rockets into northern Israel on 8 October 2023, the day after its ally Hamas's deadly attack on southern Israel, which killed about 1,200 people. A further 251 were taken to Gaza as hostages.
Since 7 October, nearly 42,000 people have been killed during Israel's offensive in Gaza, according to the Hamas-run health ministry.