Gaza - A senior UN official said Saturday that teachers and other UN staff working in Gaza fear they are now targets after an Israeli air strike hit a school-turned-shelter in the territory this week.

Wednesday's strike on the UN-run Al-Jawni School in central Gaza, which is housing displaced Palestinians, killed 18 people, including six employees of the United Nations Agency for Palestinian Refugees (UNRWA).

It was the deadliest single incident for the agency in more than 11 months of war and drew international condemnation.

"One colleague said that they're not wearing the UNRWA vest anymore because they feel that that turns them into a target," UNRWA senior deputy director Sam Rose told AFP on Saturday after visiting the shelter in Nuseirat.

"Another one said that that morning, their children had stopped them from coming into the shelter," he said in an online interview from Gaza.

The colleagues were gathering for a post-work meal in a classroom when the strike flattened part of the building, leaving only a charred heap of rebar and concrete.

"A son of one of the staff had brought a meal into the building," Rose said, adding the group then debated whether to eat it in the principal's office before settling on what appeared to be a classroom decorated with pictures of scientists.

"They were eating when the bomb hit."

The Israeli military claimed it had conducted a "precise strike" on Hamas militants within the school grounds and had taken steps to reduce the risk to civilians.

The Israeli military published what it said was a list of nine militants killed in the Nuseirat strike, including three it said were employees of UNRWA.

An Israeli government spokesman alleged the school had become "a legitimate target" because it was used by Hamas to launch attacks.

Rose said such statements further battered morale among UN staffers still at the school, where thousands have sought shelter from a war that has displaced nearly all of Gaza's 2.4 million population at least once.

"They were particularly angry by the allegations that had been made as to the involvement of their colleagues in extremist and terrorist activities," Rose said.

"They felt that this really was a stain on the memory of dear colleagues, dear friends," he added, describing the mood as "bereft" and "desperate."

UNRWA has said at least 220 members of the agency's staff have been killed amid Israel's unrelenting assault on Gaza.

On Friday, UNRWA announced one of its employees was killed during an Israeli raid in the occupied West Bank, the first such death in the territory in more than a decade.

UNRWA has more than 30,000 employees in the Palestinian territories and elsewhere. It has been in crisis since Israel accused a dozen of its employees of being involved in the October 7 attack.

The UN immediately fired the implicated staff members, and a probe found some "neutrality-related issues" but stressed Israel had not provided evidence for its main allegations.