Hezbollah was in turmoil Saturday after Israel took out two leaders of its elite operations unit in a strike on a command meeting in a Beirut stronghold that Lebanese authorities said killed 31 people.
Lebanese 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.
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.
It said it also targeted a "Hamas command and control centre" in Gaza City it alleged was "embedded inside" a school where rescuers said 19 civilians were killed in adjacent buildings used as a shelter.
Abiad said emergency services worked "through the night" to recover dead and wounded 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.
Coming after sabotage attacks on communications devices that killed 37 people in Hezbollah strongholds, Friday's strike raised new questions about the Iran-backed group's security arrangements.
Hezbollah said a second senior commander, Ahmed Mahmud Wahbi, was also killed. 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.
It also followed sabotage attacks on pagers and two-way radios used by Hezbollah on Tuesday and Wednesday, which killed 37 people.
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.
