Around 100 Palestinians have been killed and dozens have been wounded in an Israeli air strike on a school sheltering displaced people in the Daraj district, east of Gaza city, according to Palestinian authorities.
Video from the site showed body parts scattered on the ground and more bodies being carried away and covered in blankets on the floor.
Empty food tins lay in a puddle of blood and burnt mattresses and a child's doll lay among the debris.
Gaza's government media office said in a statement that the strikes hit when people sheltering at the school were performing Fajr (dawn) prayers, leading to many casualties.
"So far, there are more than 93 martyrs, including 11 children and six women. There are unidentified remains," said spokesperson for the Palestinian Civil Defence, Mahmoud Bassal, in a televised news conference.
The Israel Defense Forces (IDF) disputed the figures, saying they "do not align with the information held by the IDF".
The Gaza health ministry has so far not provided casualty details.
A statement from Gaza's civil defence agency described the strike as a "horrific massacre" with some bodies catching fire.
"Three Israeli rockets hit the school that was housing displaced Palestinians," Mr Bassal said.
Ismail Al-Thawabta, director-general of the Gaza government media office, said the number of casualties is likely to rise as al-Ahli Hospital, where the wounded were taken, struggled to cope with the influx of patients, "most of which are in severe and critical condition".
He told Al Jazeera News that the Israeli army used three 2,000-pound bombs in its air strike.
Gaza government media sources said the school was housing about 250 people, half of them women and children.
Tens of thousands of displaced Palestinians have sought shelter in Gaza's schools, most of which have stopped functioning since the start of the war 10 months ago.
The Israel Defense Forces (IDF) confirmed on X that they had attacked the Al-Tabi'een school in the Daraj neighbourhood, but claimed it was harbouring Hamas militants.
It said it struck a Hamas "command and control centre" that was "embedded" in the school "which is used as a shelter for the residents of Gaza City".
"The headquarters was used by the terrorists of the terrorist organisation Hamas to hide and from there they planned and promoted terrorist operations against the IDF forces and the citizens of the State of Israel," the IDF said.
"Before the attack, numerous steps were taken to mitigate the risk of harming civilians, including the use of precise munitions, aerial surveillance, and intelligence information."
It did not immediately provide evidence supporting those claims, but later an Israeli military spokesperson claimed around 20 Hamas and Islamic Jihad militants were operating from the school.
"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 added that casualty figures given by the Hamas-run media office "do not align with the information held by the IDF, the precise munitions used, and the accuracy of the strike."
Hamas denounced the strike as a "horrific crime that constitutes a dangerous escalation", saying it is yet another in a series of unprecedented war crimes and massacres.
It also accused the United States of being complicit by continuing to support Israel.
Izzat El-Reshiq, a member of Hamas' political office, said in a statement that the dead did not include a "single combatant".
Nabil Abu Rudeineh, a spokesperson for Palestinian President Mahmoud Abbas, urged Washington to put an end to the "blind support that leads to the killing of thousands of innocent civilians, including children, women, and the elderly".
Ceasefire talks to resume next week
The air strike comes as the United States, which has sent extra warships and jets to the region to support Israel, has urged both Iran and Israel to avoid an escalation.
US Secretary of State Antony Blinken told Israeli Defense Minister Yoav Gallant in a phone call on Friday that the escalation of tensions in the Middle East was "in no party's interest".
There has been an increased risk of escalation into a broader Middle East war after the recent killings of Hamas' leader Ismail Haniyeh in Iran and Hezbollah military commander Fuad Shukr in Beirut drew threats of retaliation against Israel.
As a result, many fear a widening of Israel's war in Gaza.
Egypt said Israel's "deliberate killing" of unarmed Palestinians shows that it lacks a political will to end the war in Gaza.
Iran has claimed that Israel wants to spread war in the Middle East, and Hamas officials, some analysts and critics in Israel have said Prime Minister Benjamin Netanyahu has prolonged the fighting for political gain.
Mr Blinken said a ceasefire agreement could result in the release of Israeli hostages taken by Hamas and "create the conditions for broader regional stability", the State Department said.
A day earlier, Mr Gallant spoke to US Defense Secretary Lloyd Austin about the situation in the region.
President Joe Biden laid out a three-phase ceasefire proposal in an address on May 31, which was later endorsed by the UN Security Council.
Washington and regional mediators have since tried arranging the Gaza ceasefire-for-hostages deal but have consistently run into obstacles.
There has been only one, week-long truce in the Gaza fighting, in November.
US, Qatari and Egyptian mediators have for months tried to secure a second one.
In a joint statement on Thursday, the three countries' leaders invited the warring parties to resume talks on August 15 in Doha or Cairo "to close all remaining gaps and commence implementation of the deal without further delay".
Mr Netanyahu's office said Israel would send negotiators "to conclude the details of implementing a deal".
EU chief Ursula von der Leyen expressed her support for the ceasefire talks on X.
"We need a ceasefire in Gaza now," she said.
"I strongly support the efforts led by the US, Egypt, and Qatar to help achieve the peace and stability the region needs."
Hamas has yet to publicly comment on the mediators' invitation.
17 schools destroyed last month
The United Nations Office of High Commissioner for Human Rights (OHCHR) said Israel had destroyed at least 17 schools last month.
"The UN Human Rights Office is horrified by the unfolding pattern of the Israeli Defense Force (IDF) strikes on schools in Gaza killing internally displaced Palestinians seeking shelter there," they said.
More than 18 people were killed in Israeli strikes on two other schools in Gaza City only two days ago, Gazan authorities said, with Israeli authorities claiming to have struck Hamas militants.
During 10 months of war across the Gaza Strip, the military has found itself returning to some areas to fight the militants again.
"Enough!" Khan Yunis resident Ahmed al-Najjar said.
"Have mercy on us, for God's sake, the young children and women are dying in the streets. Enough!"
The IDF said on Friday that troops were operating around Khan Yunis, the southern Gaza city from which soldiers had withdrawn in April after months of fighting with Hamas.
After the military issued an evacuation order for parts of the city, AFPTV images showed a crowd of people flowing through dusty, damaged streets on foot or on donkey and motorcycle carts piled with belongings.
"We've been displaced 15 times," said Mohammed Abdeen.
By Friday, the United Nations humanitarian office OCHA estimated "at least 60,000 Palestinians may have moved towards western Khan Yunis in the past 72 hours", UN spokeswoman Florencia Soto Nino said.
The latest bloodshed in the decades-old Israeli-Palestinian conflict was triggered on October 7, 2023.
Hamas militants attacked Israel, killing 1,200 and taking about 250 hostages, according to Israeli tallies.
The Gaza health ministry says since then, Israel's military assault on the Hamas-governed enclave has killed nearly 40,000 Palestinians and displaced nearly its entire population of 2.3 million.
Health officials say most of the fatalities have been civilian.
Israel says at least a third of the Palestinian fatalities are fighters.
The International Court of Justice found in January this year that Gaza faced a "real and imminent risk of genocide" as a result of the war, which Israel denies.
ABC/Wires
