At least eight people have been killed and 59 others wounded in an Israeli air strike on the southern suburbs of Beirut, Lebanon's health ministry says.
The Israel Defense Forces (IDF) said it conducted a "targeted strike" on Friday afternoon, local time, with Israeli media reporting the target was senior Hezbollah commander Ibrahim Aqil.
Two security sources have told the Reuters news agency Aqil was killed in the attack on a building in the southern suburb of Dahiyeh, where the militant group is based.
Photos and videos from the scene show extensive damage.
Aqil was wanted by the United States government for alleged involvement in the bombing of the US embassy and US Marine Corps barracks in Beirut in 1983.
He has served as the head of Hezbollah's elite Radwan Force and Jihad Council, the group's highest military body.
People and members of the military gather at the site of the strike in Beirut. (Reuters: Mohamed Azakir)
White House national security spokesperson John Kirby said the US did not have prior knowledge of the strike and urged American citizens to leave Lebanon.
Warning sirens went off in northern Israel following the Beirut strike. Israeli media reported heavy rocket fire in the area.
Israel struck after Hezbollah fired more than 100 rockets at Israeli territory on Friday afternoon, local time.
An IDF spokesperson told the AFP news agency that "some 140 rockets were fired from Lebanon within an hour starting at 1:02pm".
Israel's ambulance service said there were no immediate reports of casualties caused by the Hezbollah rockets.
Israel's Iron Dome air defence system fires to intercept a rocket fired from Lebanon, in northern Israel. (AP: Leo Correa)
The barrage of rockets came after the Israeli military said it struck dozens of rocket launchers, which were ready for use against Israel, in its most intense strikes on southern Lebanon in nearly a year of war.
Hezbollah said it targeted Israeli military bases in retaliation for strikes on southern Lebanon. It launched "salvos of Katyusha rockets" against at least six Israeli "army headquarters" and bases, including a "main air defence base", it said.
Israel also confirmed further air strikes in southern Lebanon on Friday, local time, saying it had targeted military buildings used by Hezbollah.
Tensions have soared between Hezbollah and Israel following deadly attacks on the militant group's communications network earlier this week.
Israel said several fires broke out after Hezbollah fired rockets at it territory. (Reuters: Jim Urquhart )
Exploding pagers and walkie-talkies left 37 people dead and about 3,000 others injured across Lebanon.
Hezbollah has blamed Israel for the attacks but Israel is yet to confirm or deny its involvement.
The militant group's chief, Hassan Nasrallah, vowed on Thursday to continue daily strikes against Israel until the war in Gaza was over.
Smoke rises from the southern Lebanese village of Kfar Kila, near the border with Israel. (Reuters: Karamallah Daher)
Meanwhile, Palestinian health officials say 14 people have been killed in Gaza by Israeli forces.
Officials told the Reuters news agency that shelling by Israeli tanks killed eight people and wounded several others in the Nuseirat refugee camp in the central area of Gaza, and six others were killed in an air strike on a house in Gaza City.
In the northern town of Beit Hanoun, an Israeli strike on a car killed and wounded several Palestinians, medics said.
It was not clear how many of the casualties were combatants and how many were civilians.
The Israeli military has said that forces operating in Rafah had in recent weeks killed hundreds of Palestinian militants, located tunnels and explosives and destroyed military infrastructure.
ABC/wires