DEIR AL-BALAH, Gaza Strip – At least 25 Palestinians were killed Tuesday in an Israeli airstrike on a school-turned-refugee center in southern Gaza. Heavy bombardment in the north has forced the closure of medical facilities in Gaza City and sent thousands fleeing in search of increasingly hard-to-find refuge.

Israel’s new ground assault on Gaza’s largest city is the latest effort to combat Hamas militants who have regrouped in areas the army previously said had been largely cleared.

Large parts of Gaza City and surrounding urban areas have been razed to the ground or left behind a devastated landscape after nine months of fighting. Much of the population fled earlier in the war, but hundreds of thousands of Palestinians remain in the north.

The strike at the school entrance left at least 25 people dead, according to an Associated Press reporter who counted bodies at Nasser Hospital in Khan Younis. Hospital spokesman Weam Fares said at least seven women and children were killed, and the death toll was likely to rise.

Earlier airstrikes in central Gaza killed at least 14 people, including a woman and four children, according to two hospitals that received the bodies. Israel has repeatedly struck what it calls militant targets in Gaza since the war began nine months ago.

The military blames Hamas for the civilian deaths because the militants fight in densely populated, urban areas, but the army rarely comments on individual attacks, which often kill women and children. There was no immediate comment from the military on the school attack.

There was also no immediate report of casualties in Gaza City. Families whose relatives were injured or trapped called for ambulances, but aid workers could not reach most of the affected districts because of Israeli operations, said Nebal Farsakh, a spokesman for the Palestinian Red Crescent.

“It’s a dangerous zone,” she said.

After Israel called for evacuations from eastern and central parts of Gaza City on Monday, staff at two hospitals — Al-Ahli and the Patients Friends Association Hospital — rushed to transfer patients and closed them, the United Nations said. Farsakh said all three medical facilities run by the Red Crescent in Gaza City had been closed.

The Israeli military said Tuesday it had told hospitals and other medical facilities in Gaza City that they did not need to evacuate. But hospitals in Gaza have often closed and transferred patients at any sign of possible Israeli military action, fearing incursions.

The Episcopal Church in the Middle East, which runs Al-Ahli, said the hospital was “forced to close by the Israeli military” following evacuation orders and a wave of nearby drone strikes on Sunday.

In the past nine months, Israeli forces have occupied at least eight hospitals, leading to the deaths of patients and medical personnel, as well as massive destruction of facilities and equipment. Israel has alleged that Hamas uses hospitals for military purposes, although it has provided only limited evidence.

According to the UN humanitarian agency, only 13 of Gaza’s 36 hospitals are operational, and only partially so.

The Israeli campaign in Gaza, sparked by the October 7 Hamas attack, has killed or wounded more than 5 percent of Gaza’s 2.3 million Palestinians, according to the territory’s health ministry. Nearly the entire population has been forced from their homes. Many have been displaced multiple times. Hundreds of thousands are huddled in sweltering tent camps.

The UN humanitarian agency said the exodus in Gaza City was “dangerously chaotic” with people being ordered to flee through neighborhoods where fighting was taking place.

“People have fled in several directions, not knowing which side is safest,” the agency said in a statement. It said the city’s largest UN bakery had been forced to close and that fighting had cut off aid agencies from its warehouses.

The Israeli military has said it had intelligence showing militants from Hamas and the smaller Islamic Jihad group regrouping in central Gaza City. Israel accuses Hamas and other militants of hiding among civilians. In Shijaiyah, a Gaza City neighborhood that has been the scene of weeks of fighting, the military said it had destroyed three miles of Hamas tunnels.

Hamas has warned that the latest attacks in Gaza City could lead to the failure of ceasefire negotiations and the release of hostages.

Israel and Hamas appeared to narrow the rift in recent days, with the US, Egypt and Qatar mediating.

CIA Director William Burns met with Egyptian President Abdel Fattah el-Sissi in Cairo on Tuesday to discuss negotiations, el-Sissi’s office said. More talks were scheduled for Wednesday in Qatar, where Hamas has a political office.

But obstacles remain, even after Hamas agreed to abandon its main demand that Israel commit to ending the war as part of any deal. Hamas still wants mediators to guarantee that the negotiations will conclude with a permanent ceasefire.