At least 24 people were killed in a strike on Gaza school used as a shelter, the U.N. says.

A strike this weekend on a school run by the United Nations that was being used for shelter by thousands of displaced people in northern Gaza killed at least 24 people, a U.N. official said Sunday.

Palestinian officials had said on Saturday that many people were killed and injured in an Israeli attack on the Al-Fakhura school, which was being used as a shelter by adults and children, in the Jabaliya area of northern Gaza.

Philippe Lazzarini, the head of the U.N. agency that aids Palestinian refugees, gave a death toll on Sunday and said that there were nearly 7,000 displaced people sheltering in the school when the strike hit. He did not give a number for the wounded or suggest who was responsible.

The Israeli military said that it had received reports of an incident on Saturday in the Jabaliya area and that it was under review, adding that it was “committed to international law including taking feasible steps to minimize harm to civilians.”

Mr. Lazzarini said that another school, where some 4,000 displaced people were sheltering at the time, in Gaza City, was “directly struck” on Friday, and ambulances “could not reach the school to provide help.” His agency, UNRWA, said it believed that scores of people had been either killed or wounded, but did not have exact numbers.

At least 176 displaced people sheltering at schools run by UNRWA have been reported killed and nearly 800 wounded since the start of Israel’s bombing campaign against Gaza on Oct. 7, the UNRWA statement added. Classes have been suspended and the schools have been converted into shelters across Gaza.

The agency said that it was still verifying its figures for the numbers of dead and wounded, but that it had confirmed that at least 17 of its facilities have been directly hit.

The “large number of UNRWA facilities hit and the number of civilians killed cannot just be ‘collateral damage’,” Mr. Lazzarini said in the statement. The agency’s facilities were clearly marked as U.N. buildings and their coordinates were regularly shared with both sides of the conflict, he said, adding that “This is yet another proof that no one, and nowhere is safe in Gaza.”

The Al-Fakhura school was also hit by a strike on Nov. 4, killing at least 12 people and wounding 54 others, UNRWA said.

According to UNRWA, almost 900,000 displaced people are sheltering in the agency’s facilities across the Gaza Strip. They include many people who fled northern Gaza following Israeli orders to evacuate the area amid an escalation in ground fighting there.

Families who were sheltering at UNRWA schools in the south described overcrowded facilities where food and water were scarce.

Ihab Abedrabo said he had been sheltering with his mother, wife, and six children at a school run by the U.N. agency in the southern city of Khan Younis since a strike damaged their home.

His family, like thousands of others, had fled to the school hoping that they would be safe. But Mr. Abedrabo said this when a strike hit nearby earlier this week and sent shrapnel into the school, he again feared for his relatives’ lives.

“No place is safe,” he said. “However, I can’t think of a safer place to go.”

Abu Bakr Bashir contributed reporting from London.