Battles around hospitals have forced thousands of Palestinians to flee from some of the last shelters in northern Gaza while stranding critically wounded patients, including newborns, and their caregivers with dwindling supplies and no electricity, health officials said Monday.

The Israeli military has urged Palestinians to flee south on foot through what it calls safe corridors. But its purported drive to separate civilians from Hamas militants has come at a heavy cost, with more than two thirds of the territory’s population of 2.3 million having already fled their homes.

As Israeli troops encircled Gaza’s Shifa Hospital over the weekend, thousands fled, while hundreds of patients and displaced people remained, according to officials. World Health Organization Director-General Tedros Adhanom Ghebreyesus said Shifa “is not functioning as a hospital anymore.”

Another hospital in Gaza City, Al-Quds, was forced to shut down Sunday because it ran out of fuel. The Palestinian Red Crescent, which operates the facility, said Israeli forces are stationed nearby and that preparations are being made to evacuate some 6,000 patients, medics and displaced people.

Both sides have seized on the plight of hospitals, particularly Shifa’s, as a symbol of the larger war, now in its sixth week. The fighting was triggered by Hamas’ unprecedented Oct. 7 surprise attack into Israel, and Israel’s response has brought unseen levels of death and destruction to Gaza.

For Palestinians, Shifa evokes the suffering of civilians. Thousands of people displaced by airstrikes that have destroyed entire city blocks have sought shelter in its darkened corridors. Doctors running low on supplies perform surgery there on war-wounded patients, including children, without anesthesia. One medic shared a photo showing nine premature babies in a shared crib.

Israel says Hamas shields itself among civilians and the hospital, Gaza’s largest, is a prime example of that, claiming that the militants have a command center in and beneath the medical compound. Israel has not provided photos or videos to back up the Shifa claims, though it has shared footage of militants operating in residential neighborhoods and positioning rockets and weapons near schools and mosques.

Both Hamas and the hospital staff at Shifa deny the Israeli allegations.

A U.N. health official said many displaced families and patients with moderate injuries fled the hospital over the weekend. The official, who spoke on condition of anonymity because they were not authorized to brief reporters, said most of the remaining patients could only be relocated with ambulances and other special procedures.

Mohammed Zaqout, the director of hospitals in Gaza, said those who remain include about 650 patients, 500 medical staff and around 2,500 displaced Palestinians sheltering inside hospital buildings. That’s down from more than 20,000 people reported to be at the hospital on Saturday by the Health Ministry in Hamas-ruled Gaza.

The ministry said 32 patients, including three babies, have died since the hospital’s emergency generator ran out of fuel on Saturday. It said 36 babies, as well as other patients, are at risk of dying because there is no way to power life-saving medical equipment.

Medical Aid for Palestinians, a U.K.-based charity that has supported Shifa’s neonatal intensive care unit, said transferring critically ill infants is complex. “With ambulances unable to reach the hospital ... and no hospital with capacity to receive them, there is no indication of how this can be done safely,” CEO Melanie Ward said. She said the only option was to pause the fighting and allow in fuel.

The military said it placed 300 liters (79 gallons) of fuel near the hospital, but that Hamas militants had prevented staff from reaching it. The Health Ministry disputed that and said the fuel would have provided less than an hour of electricity.

The U.S. has pushed for temporary pauses that would allow for wider distribution of badly needed aid. Israel has only agreed to daily windows during which civilians can flee ground combat in northern Gaza along two main roads, while continuing to strike what it says are militant targets across the territory, often killing women and children.

Even so, tens of thousands of people remain in the north, where Israeli ground forces are battling Hamas.

Saib Abu Hashish said he has been trapped on the ground floor of his family home along with 27 others in Gaza City. They haven’t left the house in three days and are running out of food and water. He said their neighbors attempted to escape the area on Sunday, but Israeli forces opened fire on them.

“We want to leave but we can’t because of the bombing,” he said by phone. “If we survive the bombing, we will die from hunger.”

Those who make it to the south face a host of other difficulties. U.N.-run shelters are overflowing, trash collection is no longer possible in most places, and the lack of fuel has paralyzed water treatment systems, leaving taps dry and sending sewage into the streets. Gaza’s sole power plant was forced to shut down over a month ago, and Israel has barred the import of fuel for generators.

More than 11,000 Palestinians, two-thirds of them women and minors, have been killed since the war began, according to the Health Ministry in Gaza, which does not differentiate between civilian and militant deaths. About 2,700 people have been reported missing.

Health officials, many of whom work out of Shifa, have not updated that toll since Friday because of the difficulty of collecting information.

At least 1,200 people have died on the Israeli side, mostly civilians killed in the initial Hamas attack. Palestinian militants are holding nearly 240 hostages seized in the raid, including men, women, children and older adults. The military says 44 soldiers have been killed in ground operations in Gaza.

About 250,000 Israelis have evacuated from communities near Gaza, where Palestinian militants are still firing barrages of rockets, and along the northern border with Lebanon, where Israel and the Hezbollah militant group have repeatedly traded fire, including on Monday.