The Gaza Health Ministry said that an Israeli airstrike on Tuesday hit a Gaza City hospital filled with wounded and other Palestinians in search of shelter, killing hundreds, according to The Associated Press, marking — if confirmed — the deadliest Israeli airstrike in five wars fought since 2008. The health ministry, which is run by Hamas, said at least 500 people had been killed at Al-Ahli Arabi Hospital, while a Gaza civil defense chief, whose department is also Hamas-run, said on Al-Jazeera television that more than 300 people were killed, per Reuters.

Photos said to have been from the hospital shared widely on social media showed fire overtaking the building, widespread damage and bodies dispersed among the wreckage. The AP could not independently verify the images. Several hospitals in Gaza have become refuges for hundreds of people hoping to evade attacks after Israel ordered all residents of the city and surrounding areas to evacuate to the southern part of the Gaza Strip. Hamas, whose attack last week killed more than 1,400 Israelis and sparked the latest war, called Tuesday’s hospital strike “a horrific massacre,” adding in a statement that most of the casualties were displaced families, patients, children and women.

Israeli military spokesman Rear Adm. Daniel Hagari told the AP that the Israel Defense Forces are looking into the reported strike. “We will get the details and update the public. I don’t know to say whether it was an Israeli air strike,” he said. He said — per CNN — that it is still unclear whether the hospital was hit by an Israeli Air Force strike or a failed Hamas launch.