The UN agency for Palestinian refugees says six of its employees have been killed in an Israeli air strike on one of the schools it runs in central Gaza.

Gaza’s Civil Defence spokesperson Mahmud Bassal said 18 people were killed in the strike on al-Jaouni school in Nuseirat refugee camp, which is being used as a shelter by thousands of displaced Palestinians.

Israel’s military says it carried out a “precise strike on terrorists” planning attacks from the school, and that it had taken measures to avoid harm to civilians.

UN Secretary General Antonio Guterres said the attack amounted to “dramatic violations of international humanitarian law” in a post on X .

Unrwa said the attack marked “the highest death toll among  their staff in a single incident” since the start of the war between Israel and Hamas in October.

 The body said it was the fifth time the school had been hit over the past 11 months.

Meanwhile, UN spokesman Stéphane Dujarric told reporters the UN condemned “all air strikes that target civilians and those that also target UN facilities”.