The health ministry in Hamas-run Gaza said at least 15 people were killed Saturday when a UN school sheltering thousands of displaced Palestinians was hit by an Israeli strike.
"The massacre at the Al-Fakhura school committed by the occupation (Israel) this morning left 15 martyrs and 70 wounded," ministry spokesman Ashraf al-Qudra told a press conference.
The United Nations agency for Palestinian refugees said its school is being used as a "shelter for displaced families".
"At least one strike hit the school yard where there were tents for displaced families. Another strike hit inside the school where women were baking bread," UNRWA said in a statement.
There was no immediate comment from the Israeli military about hitting the school in Jabalia refugee camp, and AFP was unable to independently confirm the toll.
On Thursday, UNRWA said four of its schools in the Gaza Strip housing people displaced by the war had been damaged by bombings.
An estimated 1.4 million people have been displaced in four weeks of war, out of the territory's 2.4 million residents, with many crammed into schools or hospitals.
The health ministry said Saturday at least 9,488 people have been killed across Gaza, the majority civilians, since Israel started pounding the territory on October 7.
The strikes came in retaliation for attacks the same day on Israel by Hamas militants in which some 1,400 people were killed, also mostly civilians, according to Israeli officials, who have vowed to destroy Hamas.
Israel, Lebanon's Hezbollah engage in cross-border clashes
The Israeli military and powerful Lebanese movement Hezbollah engaged in cross-border clashes on Saturday, with both claiming to have hit each other's positions along the frontier.
The latest skirmishes came a day after Hezbollah chief Hassan Nasrallah warned that the war between Israel and Hamas in the Gaza Strip could turn into a regional conflict if Israel pushed on with its offensive in the Palestinian territory.
On Saturday, the Israeli military said it had struck "two terrorist cells" and a Hezbollah post after an attempted attack from Lebanon.
"In response to two terrorist cells attempting to fire from Lebanon toward Israeli territory, the IDF (military) struck the cells and a Hezbollah observation post," a military statement said.
It said it had also responded to mortar fire from Lebanon into northern Israel, where no casualties were reported.
Hezbollah said it had simultaneously attacked five Israeli positions along the border.
Hours later it announced a new attack on the Al-Abbad Israeli position without specifying what kind of weapon was used.
Israel's military said in a new statement that its fighter jets struck "terror targets" of Hezbollah, accompanied by tank and artillery fire.
"The Hezbollah targets struck include terror infrastructure, rocket storage sites and military compounds," it said.
- Hezbollah chief blames US -
The Lebanon-Israel border has seen regular cross-border shelling over the past month, with firing between the Israeli military on one side and the powerful Hezbollah and its allies on the other.
In his first speech since the Israel-Hamas war broke out four weeks ago, Nasrallah warned Friday that "all options" were open for an expansion of the conflict to Lebanon as he blamed the United States for the war in Gaza.
"America is entirely responsible for the ongoing war on Gaza and its people, and Israel is simply a tool of execution," Nasrallah said in a televised broadcast, calling the conflict "decisive".
"Whoever wants to prevent a regional war -- and this is addressed to the Americans -- must quickly stop the aggression on Gaza," he said.
Since October 7, Israel has been engaged in a fierce war with Gaza rulers Hamas after the Palestinian militant group carried out a deadly attack in southern Israel that killed 1,400 people, mainly civilians, according to Israeli officials.
Israel has retaliated with relentless strikes and a ground invasion of Gaza, where more than 9,400 people, also mostly civilians, have been killed according to the health ministry in the Hamas-run territory.
'I want my legs back': the child amputees of Gaza's war
Layan al-Baz cries in agony when the effect fades of the painkillers she receives after her legs were amputated -- the result of a strike on Gaza as Israel fights Hamas.
"I don't want a false leg," the 13-year-old Palestinian tells AFP in Khan Yunis's Nasser hospital, in the southern Gaza Strip, where getting artificial limbs was nearly impossible anyway.
The impoverished Palestinian territory, under a crippling Israeli-led blockade for years and besieged since war erupted on October 7, suffers severe shortages of food, water and fuel, and medical supplies are scarce.
"I want them to put my legs back, they can do it," Baz says in desperation from her bed at Nasser's paediatric ward.
Every time she opens her eyes as the painkillers wear off, she sees her bandaged stumps.
Her mother, Lamia al-Baz, 47, says Layan was wounded last week in a strike on Al-Qarara district of Khan Yunis, part of Israel's unrelenting military campaign in response to bloody Hamas attacks on October 7 that Israeli officials say killed more than 1,400 people, most of them civilians.