Israel struck Hezbollah's stronghold in southern Beirut on Tuesday, saying it had targeted a Hezbollah commander. The target has been later identified as Fuad Shukr, who is leading the group's operations against Israel in south Lebanon.

"The army carried out a targeted strike in Beirut on the commander responsible for the murder of the children in Majdal Shams and the killing of numerous additional Israeli civilians," the military said in a statement. referring to Saturday's rocket attack in the annexed Golan Heights.  

Four people, including two young siblings, were killed and at least 70 others were wounded in the strike, as per Lebanon's Health Ministry. 

Minutes after the explosions rocked Beirut, Israeli Defence Minister Yoav Gallant posted on social media site X that "Hezbollah crossed the red line".

A senior official said Israel did not want to “escalate” the situation but had sent a “very strong message” by targeting Fuad Shukr, whom it said was responsible for the Golan Heights attack on Saturday that killed 12 people on a football pitch.

“We don’t want this to escalate into a wider war and ultimately whether this escalates or not very much depends on how Hezbollah reacts now,” the official told CNN.

Bloomberg also quoted a senior Israeli official as saying that no further military activity should be expected at this moment.

Al-Arabiya news channel cited sources familiar with the matter as saying that Israel had informed Washington ahead of the strike. 

An AFP photographer on the ground said the last floor of an eight-story building was hit and that ambulances had converged at the site of the strike.

The fate of Shukr, who goes by the nom de guerre Mohsen Shukr, is still unknown amid contradicting reports. While Israel's military confirmed that Shukr was indeed killed in the attack, Hezbollah has yet to release a statement regarding the latter's fate. 

Shukr is the successor of Hezbollah's top commander Imad Mughniyeh, killed in a 2008 car bombing in Damascus that the Iran-backed group blamed on Israel, the source said.

In 2017, the US Treasury offered $5 million for information on Shukr, describing him as "a senior adviser" to Hezbollah leader Hassan Nasrallah and saying he had "a central role" in the deadly 1983 bombing of the US Marine Corps barracks in Beirut.

Caretaker Prime Minister Najib Mikati denounced the "criminal act", deeming it as a link in a series of aggressive operations that claim civilians in clear violation of international law and international humanitarian law.

"This is something we place in the direction of the international community, which must bear its responsibilities and press with all force to oblige Israel to stop its aggression and threats and implement international resolutions," he said in a statement.

Lebanon's Foreign Minister Abdallah Bou Habib condemned the Israeli strike, saying that the government is planning to file a complaint to the United Nations over it.

"We were not expecting them to hit Beirut and they hit Beirut," he told Reuters, saying he hoped Hezbollah's response would be proportionate in order to avoid further escalation. 

Iran's embassy in Beirut also condemned "the sinful and cowardly Israeli aggression" that targeted the southern suburb of Beirut, which claimed the lives of a number of martyrs and wounded.

The White House spokesperson reiterated via Reuters the United States' "ironclad and unwavering" commitment to Israel's security in the face of all Iran-backed threats, including Hezbollah, stressing that the U.S. is working on a diplomatic solution that will allow citizens to safely return to their homes.