“A number of missions to assess the situation were denied. Yesterday evening, the U.N. finally managed to reach the affected areas to treat trauma patients, bring medical supplies and evacuate injured patients to Rafah,” said White.

“Persistent attacks on civilian sites in Khan Younis are utterly unacceptable and must stop immediately. People are being killed and injured. As fighting intensifies around hospitals and shelters hosting the displaced, people are trapped inside and lifesaving operations are impeded.”

Khan Younis’ remaining hospitals, including Nasser and Al Ama, had been cut off by the fighting leaving terrified staff, patients and displaced people trapped inside, said White.

Reminding both sides that international law requires every effort to be taken to protect civilians — with protection of hospitals, clinics, medical personnel and U.N. premises explicitly enshrined in law — White called for a halt to the “unacceptable and abhorrent” attacks which he said were indiscriminate and disproportionate.

“Another horrific day in Gaza,” UNWRA Commissioner General Philippe Lazzarini said in a post on X in which he noted that the compound was clearly marked as a U.N. facility and that its coordinates had been provided to Israeli authorities.

“Once again, a blatant disregard of basic rules of war.”

The Israeli military said it did not believe the attack was carried out by its forces but said it had launched an investigation which would also look at whether Hamas was responsible.

“After an examination of our operational systems, the IDF has currently ruled out that this incident is a result of an aerial or artillery strike by the IDF.”

“A thorough review of the operations of the forces in the vicinity is underway,” it added. “The IDF is also examining the possibility that the strike was a result of Hamas fire.”

The attack came as the IDF announced it had “encircled” Khan Younis after two days of fierce fighting ahead of a shift to a long-anticipated shift to a “lower intensity” operation to complete its stated war objective of destroying Hamas.

On Wednesday, the White House expressed “grave concern” following initial reports of the attack in a statement in which National Security Council spokesperson Adrienne Watson said the officials were seeking more information about what had occurred.

But NSC strategic communications coordinator John Kirby insisted Israel was transiting its military operations against Hamas to more targeted operations.

“Low-intensity operations doesn’t mean no-intensity operations,” Kirby said at a White House press briefing on Wednesday.

“They have removed a division of troops. That’s a lot of troops. That’s thousands of troops. And they are pursuing, on the ground, more targeted operations against — particularly against the leadership. They are relying less … on airstrikes.”