The air strike hit residential buildings in Dahieh, a suburb in southern Beirut.
On social media, film clips are spreading, allegedly showing the aftermath of the attack, which has caused extensive damage to a residential area.
Rescue efforts are underway among the rubble. According to the Lebanese civil defense, two buildings collapsed as a result of the attack.
Ibrahim Aqil, who held a leading position in the Iranian-backed Shia militia's military branch, is said to have been the target. The Israeli military announces that he was killed along with several other high-ranking commanders who planned a large-scale attack aimed at, among other things, civilians in northern Israel.
Dahieh is very densely populated and is often described as a strong Hizbollah stronghold, but it is also inhabited by many civilians.
Already tense situation
Friday's attack is the third attack on southern Beirut since the Gaza war broke out last October, which has led to almost daily clashes between Hizbollah and Israel in areas near the Lebanon-Israel border. It is the deadliest air strike on the capital since the war between Hizbollah and Israel in 2006.
The attack represents an escalation from the already very tense situation between Israel and Hizbollah due to large-scale attacks where personsökare and walkie-talkies linked to Hizbollah exploded in mainly Lebanon this week. In the attacks, at least 37 people were killed and several thousand injured when many of the blasts occurred in both family homes and public environments.
Hizbollah has already responded with new rocket attacks on northern Israel, which are said to have been aimed at an intelligence headquarters that the militia accuses of being behind the Beirut attack.
Has sworn revenge
Earlier on Friday, rockets from Hizbollah rained down on northern Israel on a large scale. The Israeli military counts around 150 projectiles.
On Thursday, the Israeli air force attacked hundreds of targets in Lebanon. This happened simultaneously with Hizbollah's top leader Hassan Nasrallah holding a speech where he swore to avenge the exploding communication units.
