Dozens of people are believed to have been killed in an Israeli airstrike on a school building.

An Israeli air strike on a school sheltering displaced Palestinians in Gaza City has killed more than 70 people, a hospital director has told the BBC.

Fadl Naeem, director of al-Ahli Hospital, which received many of the casualties, said these were the victims who had been identified so far, while the bodies of many other victims were so badly disfigured that they were difficult to identify.

The situation was “dire” and doctors were unable to treat the seriously injured, he said.

An Israel Defense Forces (IDF) spokesman said the al-Taba’een school “operates as a military base for Hamas and Islamic Jihad” with around 20 “fighters” operating there. Hamas denied this.

Earlier estimates of the death toll also ran into the dozens, with the Hamas-run health ministry ambulance service saying more than 60 people had died. The civil defense agency put the figure at more than 90, according to the AP.

The BBC could not independently verify the figures from either side.

Israel has attacked several such shelters in Gaza in recent weeks.

According to the United Nations, as of July 6, 477 of the 564 school buildings in Gaza had been directly hit or damaged, and at least 14 more schools have been attacked since.

Al-Taba’een School is home to more than 1,000 people – it recently took in dozens of evacuees from the town of Beit Hanoun, after the Israeli army ordered them to leave their homes.

Witnesses said the building was also a mosque and the Israeli airstrike occurred during dawn prayers.

Jaafar Taha, a student who lives near the school, told the BBC that the bomb was followed by screaming and noise.

“‘Save us, save us,’ they shouted,” he said.

“The scene was horrific. Body parts were everywhere and blood covered the walls.”

Salim Oweis, a spokesman for the UN children’s agency Unicef, told the BBC the attack was “truly senseless”.

“All those schools were packed with people, children, mothers and families, who had to take shelter in any open space, whether it was a school or a mosque, whatever it was, even in the hospital yard.”

The Israeli military said it had “precisely targeted Hamas terrorists operating in a Hamas command and control center located in al-Taba’een school”.

In a statement, Israel Defense Forces (IDF) spokesman Lieutenant Colonel Nadav Shoshani said “based on Israeli intelligence, approximately 20 Hamas and Islamic Jihad militants, including senior commanders, were operating from the attacked complex at al-Tabaeen school, using the site to carry out terrorist attacks.”

The Israeli spokesman said the casualty figures released by Hamas officials “do not match the information held by the IDF, the exact type of ammunition used and the accuracy of the airstrikes”.

Hamas described the attack as a “horrific crime and a dangerous escalation” in Israel’s “genocidal war against the Palestinian people”.

Fatah, Hamas’s Palestinian political rival in the Israeli-occupied West Bank, said Israel’s goal was to “exterminate the Palestinian people through a policy of mass murder”.

Philippe Lazzarini, head of Unrwa, the UN agency helping Palestinians, said “it is time for the horrors taking place under our watch to end”.

British Foreign Secretary David Lammy said he was “appalled” by the “tragic casualties” and stressed the need for an “immediate ceasefire”.

The reported casualty figure in the early Saturday morning attack was higher than in most similar attacks.

But targeting school buildings has become a regular IDF operation in recent weeks, apparently part of an ongoing effort to destroy Hamas’ military infrastructure.

According to unofficial statistics, more than a dozen schools have been affected since the beginning of July, including at one point four schools in just four days.

Each time, in nearly identical statements, the IDF has said that Hamas is hiding in schools and using them as command centers to plan and carry out attacks, something Hamas denies.

Regardless, these buildings are home to many of Gaza’s displaced residents, and they are paying the highest price.

Many schools were run by the United Nations before the war, and the United Nations strongly condemned the air strikes.

It was unclear whether the incident would affect struggling efforts to reach a ceasefire, which were hampered by the assassination of Hamas political leader Ismail Haniyeh in Iran last month.

But Egypt, one of the mediators involved in efforts to reach a ceasefire, said Israel’s “targeted killings” of unarmed Palestinians showed Israel lacked the political will to end the war.

Jordan and Türkiye also expressed similar concerns.

Hamas-led gunmen killed some 1,200 people in an attack on Israel on October 7, taking 251 others back to Gaza as hostages.

That attack sparked a major Israeli military offensive on Gaza and the ongoing war.

According to the Hamas-run Gaza Health Ministry, more than 39,790 Palestinians have been killed in the Israeli campaign.

Additional reporting by Rushdi Abualouf, Gaza correspondent in Istanbul, Türkiye