United Nations Secretary-General Antonio Guterres has said that Israeli air strikes on a school-turned-shelter in Gaza killed six staffers from the UN Palestinian Refugee Agency (UNRWA), AFP reports.

“What’s happening in Gaza is totally unacceptable,” Guterres said in a post on social media platform X.

“Six of our UNRWA colleagues are among those killed.”

UNRWA called it the highest death toll among its staff in a single incident.

“This school has been hit five times since the war began. It is home to around 12,000 displaced people, mainly women and children,” UNRWA separately posted on X.