The United States White House said it was “deeply concerned” about an Israeli air strike on a Gaza City school compound that local civil defence officials say killed 100 people, adding to condemnation of the attack from several Arab states, Turkey, Britain, and the European Union’s foreign policy chief.

The school compound in Gaza City housed displaced Palestinian families.

The Gaza Civil Emergency Service, which has a credible record on stating casualty numbers, said about 100 people were killed in Saturday’s strike. Israel said about 20 militants had been operating at the compound.

Video from the site showed body parts scattered among rubble and more bodies being carried away and covered in blankets.

“We are deeply concerned about reports of civilian casualties in Gaza following a strike by the Israel Defence Forces on a compound that included a school,” the White House said in a statement, adding that Washington was in touch with Israel to seek more information.

Washington has faced mounting domestic and international criticism, including from human rights groups, for its military support for Israel.

Saturday’s air strike came a day after a State Department spokesperson said the US will provide Israel with US$3.5 billion ($5.8b) to spend on US weapons and military equipment after Congress appropriated the funds in April.

“We know Hamas has been using schools as locations to gather and operate out of, but we have also said repeatedly and consistently that Israel must take measures to minimise civilian harm,” the White House added.

The statement also said “far too many civilians continue to be killed and wounded” in the Gaza war and reiterated calls for a ceasefire.

The US comments followed condemnation of the attack from Egypt, Qatar, the United Arab Emirates, Saudi Arabia, and Turkey. EU foreign policy chief Josep Borrell said he was horrified by the images from the school, while Britain’s Foreign Secretary David Lammy said he was “appalled” by the strike.

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Tens of thousands of displaced Palestinians have sought shelter in Gaza’s schools, most of which have been closed since the war began 10 months ago.

The strike marked the latest deadly attack in Israel’s assault on Gaza which the health ministry in the Hamas-governed enclave says has killed nearly 40,000 Palestinians while also displacing nearly the entire population of 2.3 million, causing a hunger crisis and leading to genocide allegations at the World Court that Israel denies.

The latest bloodshed in the decades-old Israeli-Palestinian conflict was triggered on October 7 when Hamas attacked Israel, killing 1200 and taking about 250 hostages, according to Israeli tallies.

US President Joe Biden laid out a three-phase ceasefire proposal in an address on May 31. Washington and regional mediators have tried to nail the Gaza ceasefire-for-hostages deal but have run into repeated obstacles.

There has separately been an increased risk of a broader Middle East war after the killings of Hamas political leader Ismail Haniyeh in Iran and Hezbollah military commander Fuad Shukr in Beirut drew threats of retaliation against Israel.