More than 100 Palestinians have been killed and dozens wounded in an Israeli strike on a school sheltering displaced people in Gaza City, according to officials in the enclave.

Three Israeli bombs hit al-Tabin school, located in the Daraj district, Gaza’s civil defence agency said of the attack on Saturday, which it described as a “horrific massacre”.

Women, children and the elderly are reported to be among the dead and the toll was expected to rise. The attack took place while people were performing morning prayers and triggered a fire that ripped through the building.

Ismail al-Thawabta, the head of Gaza’s Government Media Office, told Al Jazeera that the Israeli army used three bombs weighing 2,000 pounds (907kg) each in its attack.

He said Israel was aware of the presence of displaced people inside the school.

The Israeli military said its air forces struck a “command and control centre” that “served as a hideout for Hamas terrorists and commanders”.

Without providing evidence, the Israeli military said in a separate statement that it had intelligence indicating there were 20 Hamas and Islamic Jihad fighters, including senior commanders, operating from the school.

It also said that the civilian casualty figures given by Palestinian authorities were inaccurate.

Israeli forces have repeatedly attacked schools used as shelters in Gaza, claiming they are command centres for Hamas, the Palestinian group that governs the territory, to hide fighters and manufacture weapons.

Saturday’s attack was the fourth such incident in a week. Hamas has denied Israeli accusations that it operates from civilian facilities such as schools and hospitals.

The attack was condemned by Qatar and Egypt – two of the key mediators leading negotiations for a ceasefire – among several other countries. Palestinian political factions, as well as NGOs and the United Nations agency for Palestinian refugees (UNRWA) also denounced the strike.

Palestinian journalist Hossam Shabat reported that rescue teams were unable to help those trapped by the flames as the Israeli military cut water access to the area.

Many of the wounded rushed to the al-Ahli Hospital in Gaza City were in a critical condition, severely bleeding from shrapnel or severely burned from the fire that broke out from the bombardment, said Al Jazeera’s Hani Mahmoud, reporting from Khan Younis in southern Gaza.

“Many are arriving either soaked in blood or already pronounced dead,” Mahmoud said, adding that the medical facility was on the brink of collapse and unable to provide adequate medical care.

Some of the bodies were hard to recognise, “so relatives at the hospital searching for their loved ones are struggling to find any way to identify them”, he added.

Mahmoud Basal, a spokesman for the civil defence agency, said: “The school area is strewn with dead bodies and body parts. It is very difficult for paramedics to identify a whole dead body. There’s an arm here, a leg there. Bodies are ripped to pieces.”

Al Jazeera’s Mahmoud said among those killed were survivors of attacks in different evacuation centres over the last 10 days.

“They had lost family members, they were on their own and they were seeking shelter and protection at this particular school-turned-evacuation centre,” he said. “That means entire families are being obliterated and wiped off the civil registry across the Gaza Strip.”

The bombing comes as Qatar, Egypt and the United States have called on Israel and Hamas to resume talks on August 15 to reach a ceasefire.

“But every time we get closer to any sort of negotiations for a ceasefire, there is some sort of large-scale Israeli attack that completely derails these discussions,” said Al Jazeera’s Hamdah Salhut, reporting from Amman, Jordan.

Hassan Barari, a professor of international affairs at Qatar University, said the attack was part of Israel’s strategy to thwart peace efforts.

“They’ve been targeting hospitals and now schools. And this is a reflection of an Israeli mindset that wants to make Gaza really a hard place to live in,” Barari told Al Jazeera, adding this was a pressure tactic to get concessions from Hamas in any future talks.

“We have seen this movie before,” Barari said. “Every time there was talk about peace talks and about truth, the Israelis would do something to undermine the effort. And I think this is clear this time that [Israeli Prime Minister Benjamin] Netanyahu is trying to preempt the talks on Thursday.”

Gaza’s Ministry of Health said on Saturday that at least 39,790 people have been killed and 92,002 wounded in Israel’s war on the enclave.

An estimated 1,139 people were killed in Israel during the Hamas-led attacks on October 7 and more than 200 were taken captive.