“At least 50 people” were killed in a dawn strike on the UN-run Al-Fakhura school in the camp, the ministry official told AFP, sparking condemnation from the UN agency for Palestinian refugees (UNRWA).
Denouncing the “horrifying images and footage of scores of people killed and injured” in the school, UNRWA chief Philippe Lazzarini said such attacks “cannot become commonplace, they must stop”.
The school had been converted into a shelter for “thousands” of displaced Palestinians, Lazzarini posted on X, formerly Twitter.
Social media videos — which was not able to verify — showed bodies covered in blood and dust on the floor of a building, where mattresses had been wedged under school tables.
Jabalia, in the northern Gaza Strip, is the biggest refugee camp in the Palestinian territory, where some 1.6 million have been displaced by more than six weeks of fighting between Israel and Hamas.
Earlier this month, the health ministry said 15 people were killed by an Israeli strike at the same school. UNRWA said four of its schools in the Gaza Strip housing people displaced by the war had been damaged by bombings.
A separate strike on another building in the Jabalia camp on Saturday killed 32 people from the same family, 19 of them children, the health ministry official said.
The ministry released a list of 32 members of the Abu Habal family it said had died.
The Israeli army did not specifically comment on the strikes but in a statement said its troops were expanding operations in the Gaza Strip, including in parts of Jabalia, to “target terrorists and strike Hamas infrastructure”.
At the start of November, the Hamas government said more than 200 people had been killed and hundreds more wounded in three straight days of Israeli bombardment of Jabalia.
Israel has vowed to destroy Hamas in response to the October 7 attacks which Israeli officials say killed about 1,200 people, most of them civilians, and saw about 240 people taken hostage.
The army’s relentless air and ground campaign has since killed 12,000 people, including 5,000 children, according to the Hamas government which has ruled Gaza since 2007.