Israel-Gaza updates: Houthis claim 'hypersonic' missile attack on Israel

United Nations Secretary-General António Guterres accused Israel of "dramatic violations of international humanitarian law" over its continued airstrikes on schools-turned-shelters in the Gaza Strip.

Six United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNWRA) were among at least 17 people killed in a Wednesday strike on the Al-Jaouni School in Nuseirat in central Gaza, the agency confirmed. It is the fifth time that the school has been targeted since Oct. 7.

Guterres wrote on X: "What's happening in Gaza is totally unacceptable. A school turned shelter for around 12,000 people was hit by Israeli airstrikes again today." The attacks "need to stop now," he added.

UNRWA Commissioner-General Philippe Lazzarini wrote on X: "Endless & senseless killing, day after day."

"Humanitarian staff, premises & operations have been blatantly & unabatedly disregarded since the beginning of the war," he added, noting that at least 220 UNRWA staff have been killed in Gaza.

"The longer impunity prevails, the more international humanitarian law & the Geneva conventions will become irrelevant," he wrote, adding it was time for both a cease-fire and "accountability."

The Israel Defense Forces said Wednesday that the strike targeted "a Hamas command and control center in the area."

Israel's Coordination of Government Activities in the Territories body hit back at Lazzarini's social media complaint, alleging in its own post that Gaza schools "have been Hamas weapons storage facilities, tunnel access points, and bases of operation for over a decade."

"Maybe if you hadn't turned a blind eye to Hamas's use of UNRWA schools, the current situation would be entirely different," the organization wrote.

-ABC News' Jordana Miller, Will Gretsky and Victoria Beaule

Aysenur Eygi's family responded to President Joe Biden's statement released earlier Wednesday where he called her death "totally unacceptable."

The family said that Biden has not called them.

"Let us be clear, an American citizen was killed by a foreign military in a targeted attack. The appropriate action is for President Biden and Vice President [Kamala] Harris to speak with the family directly, and order an independent, transparent investigation into the killing of Ayşenur, a volunteer for peace," the family said in a statement.

-ABC News' Elle Kaufman

Search and rescue operations are ongoing after an Israel Defense Forces strike on a school in Gaza killed at least 17 people and wounded over 18 others, according to Gaza Civil Defense.

This is the fifth time the IDF has bombed this school. It was previously struck by the IDF on July 6.

Six of the people killed in the strike worked for the United Nations Relief and Works Agency for Palestine Refugees in the Near East, according to the agency. Among those killed was the manager of the UNRWA shelter and other team members providing assistance to displaced people.

About 12,000 displaced people live in the school, mainly women an children, according to the UNRWA.

The IDF, confirming the strike, claimed that the school had been used by Hamas terrorists to plan and execute attacks against Israel.

An Israeli air force helicopter crashed in the Rafah area of the Gaza Strip, killing two soldiers overnight Tuesday into Wednesday, the Israel Defense Forces said.

The helicopter was "on a mission to evacuate an injured solider to a hospital for medical treatment," the IDF said. An initial inquiry "indicates the crash was not caused by enemy fire," but the cause of the crash is still "under investigation," the IDF said.

Seven additional soldiers were injured "to varying degrees" and were evacuated to a hospital for treatment, the IDF said.

The families of the killed and injured soldiers have been notified, the IDF said.

-ABC News' Jordana Miller