The White House has said it is "deeply concerned" about an Israeli airstrike on a Gaza City school compound that, according to local health officials, killed around 100 people.
"We are deeply concerned about reports of civilian casualties in Gaza" following the strike, National Security Council spokesman Sean Savett said in a statement,
Mr Savett added that the US was "asking for further details".
He said the strike, which has prompted international condemnation, "underscores the urgency of a ceasefire and hostage deal, which we continue to work tirelessly to achieve".
The Hamas-run Gaza government said that an Israeli airstrike on the school compound killed around 100 people, while the Israeli military said it had targeted Hamas militants and cast doubt on the Palestinian death toll.
Video from the site showed the destruction caused by the attack.
Empty food tins burnt mattresses and a child's doll lay among the debris.
In another video, men prayed over a dozen body bags laid out on the ground.
It was not immediately clear whether all the videos were filmed on the ground floor of the Tabeen school complex, in Gaza City.
Gaza's Hamas-run media office said in a statement that the complex was attacked when people sheltering there were performing dawn prayers.
"So far, there are more than 93 martyrs, including 11 children and six women," Palestinian Civil Defence spokesperson Mahmoud Bassal told a televised press conference.
"There are unidentified remains," he added.
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Around 350 families had been sheltering at the compound, Mr Bassal said - some of the hundreds of thousands of Palestinians displaced from their homes by Israel's onslaught on Gaza.
The upper floor housing families and the lower floor, used as a mosque, were both hit, he said.
The Gaza health ministry did not immediately provide casualty details.
The Israeli military said the death toll was inflated and that around 20 militants had been operating at the site.
"The compound and the mosque that was struck within it, served as an active Hamas and Islamic Jihad military facility," Lieutenant Colonel Nadav Shoshani said on X.
He said the numbers published by the Hamas-run media office did not appear to correspond to the Israel Defence Forces' information.
A military official said the part of the mosque that was struck was reserved for men.
"This was verified by intelligence, and the strike was carried out using three small, precise munitions which cannot cause the scale of damage that the Palestinians are reporting," the official said.
Israel says Palestinian militants embed themselves among Gaza's civilians, operating from within schools, hospitals and designated humanitarian zones - which Hamas and its allies deny.
Hamas said the strike was a horrific crime and a serious escalation.
Izzat El-Reshiq of Hamas' political office said the dead did not include a single combatant.
In the enclave, tens of thousands of displaced Palestinians have sought shelter in schools, most of which have been closed since the war began ten months ago.
A separate strike killed three Palestinians in Al-Nuseirat in central Gaza and another killed one person in nearby Deir Al-Balah, medics said.
Ceasefire talks
The European Union's foreign policy chief Josep Borrell said on X that he was horrified by the images from the school.
A spokesperson for Palestinian President Mahmoud Abbas, Nabil Abu Rudeineh, urged Israel's ally Washington to put an end to "blind support that leads to the killing of thousands of innocent civilians, including children, women, and the elderly".
Egypt, Qatar, the United Arab Emirates Saudi Arabia and Turkey all condemned the strike.
Senior Hamas official Sami Abu Zuhri said it should serve as a turning point as mediators push to resume ceasefire talks.
A Hamas official told Reuters the group was studying a new proposal for discussion but did not elaborate.
Egypt said the killing of Gaza civilians showed Israel had no intention of ending the war.
Qatar's foreign ministry described the strike as a "horrific massacre".
Egypt, the United States and Qatar have scheduled a new round of ceasefire negotiations for Thursday, as fears grow of a broader conflict involving Iran and its Lebanese ally Hezbollah.
Israeli Prime Minister Benjamin Netanyahu, who has said he will not end the war until Hamas no longer poses a threat to Israelis, said he would send a delegation.
Israel launched its assault on Gaza after Hamas fighters attacked southern Israel on 7 October, killing 1,200 people, mostly civilians, and capturing more than 250 hostages, according to Israeli tallies.
Since then, nearly 40,000 Palestinians have been killed in the Israeli offensive in Gaza, according to the health ministry, which does not distinguish between combatants and civilians.
Health officials said most of the fatalities have been civilians, but Israel said at least a third are fighters.
Israel said it has lost 329 soldiers in Gaza, while Iran-backed Hamas does not publish its casualties.
UN expert accuses Israel of genocide
An independent UN-appointed expert accused Israel of committing "genocide" in its Gaza war after an Israeli strike targeting a school killed 93 people, according to local rescuers.
"Israel is genociding the Palestinians one neighbourhood at the time, one hospital at the time, one school at the time, one refugee camp at the time, one safe zone at the time," Francesca Albanese, the United Nations special rapporteur on the rights situation in Palestinian territories, said on social media platform X.
Israel was carrying out such strikes against Palestinians using "US and European weapons," Ms Albanese said.
"May the Palestinians forgive us for our collective inability to protect them," she added.
Israel, which has long been highly critical of Ms Albanese and her mandate, denounced her report as an "obscene inversion of reality".
She has said that "of course" she also condemned Hamas for its attack on Israel which triggered ten months of war in Gaza.
Special rapporteurs are appointed by the United Nations Human Rights Council but do not speak on behalf of the UN.
