“This is the highest death toll among our staff in a single incident,” UNRWA said in a post on the social media platform X, formerly Twitter.

The shelter manager and other UNRWA team members were among the victims.

Killings ‘totally unacceptable’: Guterres

UN Secretary-General António Guterres deplored the incident.

“What's happening in Gaza is totally unacceptable. A school turned shelter for around 12,000 people was hit by Israeli airstrikes again today. Six of our UNRWA colleagues are among those killed,” he wrote on X.

“These dramatic violations of international humanitarian law need to stop now.”

Not a target

The UNRWA school in Nuseirat, located in the Middle Area of the Gaza Strip, was sheltering displaced people, mainly women and children.

This marked the fifth time that it had been hit since the conflict began 11 months ago.

Earlier on Wednesday the UN said the site had been previously deconflicted with the Israeli forces.

UNRWA called on all parties to the conflict to never use schools or the areas around them for military or fighting purposes.

“No one is safe in Gaza. No one is spared. Schools and other civilian infrastructure must be protected at all times, they are not a target,” the tweet said.

‘Endless and senseless killing’

UNRWA Commissioner-General Philippe Lazzarini lamented the “endless and senseless killing, day after day” in Gaza.

Writing on X, he said at least 220 agency staff have lost their lives since the war began.

“Humanitarian staff, premises and operations have been blatantly and unabatedly disregarded since the beginning of the war,” he said, warning that “the longer impunity prevails, the more international humanitarian law and the Geneva conventions will become irrelevant.”

Polio campaign rolls on

Separately, the UN reported that health workers continue efforts to vaccinate young children in northern Gaza against polio, part of a wider campaign to defeat the disease, which can cause paralysis.

More than 81,600 boys and girls were vaccinated as of Tuesday, according to preliminary data from the UN World Health Organization (WHO).

Polio was detected in Gaza in June and UN agencies and partners launched a two-round campaign this month to provide over 640,000 children with two doses of novel oral polio vaccine type 2.

So far, nearly 528,000 children have been reached in the first round.

“More than 230 teams are on the ground trying to reach all children under the age of 10 with the first batch of the polio vaccination,” UN Spokesperson Stéphane Dujarric said in New York, adding that “they will need to do this again in four weeks.”

Health system in tatters

The campaign is taking place as Gaza’s healthcare system remains in dire condition.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) and partners said half of all essential medicines are not available in the enclave, while primary health centres are facing critically low levels of insulin.

Additionally, routine vaccinations to protect infants from tuberculosis, diphtheria, tetanus and pertussis, are also nearly exhausted.

West Bank military operation

The UN and partners also continue to support Palestinian civilians in the West Bank who have been affected by the 10-day Israeli security operation in Jenin and Tulkarm, as well as adjacent refugee camps.

This includes delivery of food and water, with OCHA coordinating efforts to provide additional assistance.

Over the weekend, the Office together with UNRWA and other humanitarian partners began assessing the needs of Palestinians affected by the operation.

Damage and displacement

More than 620 people, over a third of them children, remain displaced, and some 2,400 housing units have been damaged, with more than 100 rendered uninhabitable.

During the operation, more than 2.6 kilometres of water and sewage networks in the Tulkarm and Nur Shams refugee camps were bulldozed, severely hindering the delivery of essential services.

As a result, more than 33,000 residents have been coping with water cuts and sewage flooding over the past two weeks.