Gaza's civil defence agency said an Israeli strike Saturday on a school-turned-shelter in the Palestinian territory's largest city killed 21 people, while Israel's military said it targeted Hamas militants.
"Civil Defence crews recovered 21 people, including 13 children and six women", one of whom was pregnant, said agency spokesman Mahmud Bassal.
There were "around 30 injured, including nine children (needing) limb amputations, as a result of an Israeli bombing on Al-Zaytoun School C" in Gaza City, he said.
The health ministry in the Hamas-run territory also said 21 people were killed.
Thousands of displaced people had sought shelter at the school, Bassal said.
Israel's military said in a statement the air force had "conducted a precise strike on terrorists who were operating inside a Hamas command and control centre in Gaza City".
It said the target was "embedded inside" the Al Falah School, adjacent to the Al-Zaytoun School buildings.
An AFP reporter at the scene confirmed that Al-Zaytoun School C had been hit.
Witnesses said that before the strike, orphans had gathered there because they were due to receive sponsorship from a local NGO for humanitarian assistance.
Israel's military did not provide a death toll but said "numerous steps were taken to mitigate the risk of harming civilians, including the use of precise munitions, aerial surveillance and additional intelligence".
It was the latest in a series of Israeli strikes on school buildings housing displaced people in Gaza.
A strike on the United Nations-run Al-Jawni School in central Gaza on September 11 drew international outcry after the UN agency for Palestinian refugees said six of its staffers were among the 18 reported fatalities.
The Israeli military accuses Hamas of hiding in school buildings where many thousands of Gazans have sought shelter -- a charge denied by the Palestinian militant group.
Hamas on Saturday condemned the strike on Al-Zaytoun School C, describing it in a statement as "a war crime under American cover", a reference to Washington being Israel's most important military backer.
"There has also been an increase in attacks on residential neighbourhoods and tents of displaced people," the Hamas statement said.
The vast majority of the Gaza Strip's 2.4 million people have been displaced at least once by the ongoing war, which was triggered by Hamas's October 7 attack on Israel.
- 'Health ministry staffers killed' -
The war has badly battered Gaza's health sector, and the World Health Organization said earlier this month that only 17 of its 36 hospitals were partially functional.
Gaza's health ministry said on Saturday that in a separate incident, an Israeli air strike hit a warehouse in a "densely populated" area of southern Gaza, killing "three ministry of health personnel and a passer-by" and injuring six others.
"The warehouse was directly targeted with several missiles while doctors and staff were performing their duties, preparing to transport the medicines stored there to hospitals under the ministry of health that are facing severe shortages of medicines and supplies," a statement said.
Israel's military had no immediate comment on the warehouse strike.
Hamas's October 7 attack resulted in the deaths of 1,205 people on the Israeli side, most of them civilians, according to an AFP tally based on official Israeli figures, which includes hostages killed in captivity.
Out of 251 people taken hostage that day, 97 are still being held inside the Gaza Strip, including 33 who the Israeli military says are dead.
At least 41,391 Palestinians, a majority of them civilians, have been killed in Israel's military campaign in Gaza since the war began, according to data provided by the health ministry there.
The United Nations has acknowledged these figures as reliable.