Lebanon's Hezbollah movement, which has been exchanging fire with Israel for months, on Saturday announced that two commanders of its elite operations unit had been killed by an Israeli strike on Beirut, which authorities said left 37 people dead.
Health Minister Firass Abiad said three children were also killed in Friday's strike on an underground meeting room, which AFP journalists said left a huge crater in a densely populated neighbourhood of the capital's southern suburbs, a Hezbollah stronghold.
Israel said the strike killed the head of Hezbollah's elite Radwan Force, Ibrahim Aqil, and several other commanders.
The military said Saturday it was again hitting targets "belonging to the Hezbollah terrorist organisation in Lebanon", without elaborating.
The Iran-backed group later said it targeted at least seven military positions in northern Israel and the annexed Golan Heights with rockets, and AFP correspondents reported heavy Israeli strikes in south Lebanon.
Israel's military also said it targeted a Hamas command centre in Gaza City that it alleged was "embedded inside" a school, where rescuers said 21 people were killed in adjacent buildings used as a shelter.
Abiad, Lebanon's health minister, said emergency services worked "through the night" to recover victims from the Beirut strike, adding that "a residential building collapsed on top of occupants" after the Israeli attack.
The Radwan Force has spearheaded Hezbollah's ground operations, and Israel has repeatedly demanded through international mediators that its fighters be pushed back from the border.
Hezbollah said a second senior commander, Ahmed Mahmud Wahbi, was also killed on Friday. It said he headed the group's operations against Israel from the onset of the Gaza war in October until the start of this year.
Confirming the death of Aqil, who was wanted by the United States for involvement in the 1983 bombing of the US embassy in Beirut, Hezbollah hailed him as "one of its great leaders".
It was the second Israeli strike on Hezbollah's military leadership since the Gaza war began. In July, an Israeli strike on Beirut killed Fuad Shukr, a top operations chief.
Friday's strike also followed sabotage attacks on pagers and two-way radios used by Hezbollah on Tuesday and Wednesday, which killed 39 people. Hezbollah blamed Israel, which has not commented.
Hezbollah chief Hassan Nasrallah vowed Thursday that Israel would face retribution for those blasts.
Stephane Dujarric, spokesman for UN Secretary-General Antonio Guterres, said the world body was "very concerned about the heightened escalation" and called for "maximum restraint" from all sides.
Israel's military said it conducted a "targeted strike" against Aqil, which a source close to Hezbollah said killed 16 Radwan Force members.
"The command of the Radwan Force was meeting in the basement of the building," the source said.
Washington had offered a $7 million reward for information on Aqil, calling him a "principal member" of an organisation that claimed the 1983 US embassy bombing which killed 63.
- No refuge -
Israeli troops and Hezbollah fighters have battled each other along the Israel-Lebanon border since Hamas Palestinian militants triggered the war in Gaza with their October 7 attack.
Hezbollah says it is acting in support of Hamas.
After Friday's strike, Israeli Defence Minister Yoav Gallant said Israel's "enemies" would find no refuge, not even in Beirut's southern suburbs.
Military spokesman Rear Admiral Daniel Hagari said Israel was "not aiming for a broad escalation in the region", but Hamas called it a "brutal and terrorist aggression" and an "escalation".
Iran accused Israel of seeking to "broaden the geography of the war".
Months of near-daily cross-border exchanges have killed hundreds in Lebanon, mostly fighters, and dozens in Israel and the annexed Golan Heights, forcing tens of thousands on both sides to flee their homes.
- Gaza school strike -
Israeli Prime Minister Benjamin Netanyahu delayed by a day his departure for the United States, where he is due to address the UN General Assembly.
On Friday the UN's High Commissioner for Human Rights, Volker Turk, told the Security Council the attack on Hezbollah communications devices violated international law and could constitute a war crime.
The pagers and walkie-talkies exploded as their users were in supermarkets, walking on streets and attending funerals, plunging Lebanon into panic.
"I am appalled by the breadth and impact of the attacks," said Turk, adding that it "is a war crime to commit violence intended to spread terror among civilians".
International mediators, including the United States, have been scrambling to stop the Gaza war from becoming a regional conflict.
On Saturday, Gaza's civil defence agency said an Israeli strike on Al-Zaytoun School C, which had been turned into a displaced shelter, killed 21 people including 13 children and six women, one of them pregnant.
Israel's military said the Hamas militants targeted were "embedded inside" the adjacent Al-Falah School.
An AFP reporter confirmed Al-Zaytoun School C was hit.
Israel's military did not provide a death toll but said "numerous steps were taken to mitigate the risk of harming civilians".
In late August the United Nations said Israel had struck at least 23 school shelters since July 4.
Israel has repeatedly accused Hamas of operating from such facilities in highly urbanised Gaza, a charge the militants deny.
The October 7 attacks that triggered the Gaza war resulted in the deaths of 1,205 people, mostly civilians, on the Israeli side, according to an AFP tally based on Israeli official figures that include hostages killed in captivity.
Of 251 hostages seized by militants, 97 are still held in Gaza, including 33 the Israeli military says are dead.
Israel's retaliatory military offensive has killed at least 41,391 people in Gaza, most of them civilians, according to figures provided by the Hamas-run territory's health ministry. The UN has acknowledged the figures as reliable.
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