JERUSALEM — Israeli tanks surrounded the Gaza Strip’s largest hospital Wednesday as troops launched their long-anticipated raid in pursuit of the Hamas militants they accuse of operating a warren of tunnels under the facility.

The forces streamed into the facility before dawn, all but severing outside communication with the patients, medical staff and displaced families trapped in al-Shifa Hospital by day of fighting outside. By the end of the day, the tanks had withdrawn but troops remained inside the compound, Israel Defense Forces and hospital staff said.

Israeli officials, who for weeks have warned that Hamas uses medical facilities including al-Shifa as bases for its operations, described a “precise and targeted” mission.

Palestinian officials called it a “crime against humanity” that left terrified civilians to uncertain fates in a medical facility already struggling without water or fuel after days of intense bombardment by the encroaching forces. Hamas and hospital staff deny accusations that the militants operate there.

With the collapse of communications and no access for journalists, The Washington Post was unable to independently confirm conditions on the ground.

The raid drew alarm from international humanitarian groups. Tedros Adhanom Ghebreyesus, the head of the World Health Organization, said the agency had “lost touch again with health personnel at the hospital” Wednesday morning and was “extremely worried” for the safety of the facility and its patients. U.N. aid chief Martin Griffiths said he was “appalled” by the reports: “Hospitals are not battlegrounds.”

National Security Council spokesman John Kirby said Tuesday that Hamas and other militants “used some hospitals in the Gaza Strip, including al-Shifa, and tunnels underneath them, to conceal and support their military operations and to hold hostages.”

Hamas criticized the operation and accused the White House of giving Israel a “green light” to enter the hospital and endanger civilians.

Kirby told reporters Wednesday that the United States “did not give an okay” to Israel’s raid of the hospital, as it does not give prior approval to Israel’s tactical operations. “The United States is not involved in those procedures,” he said.

“We believe hospitals should be protected,” he added, echoing earlier White House statements.

Israeli Rear Adm. Daniel Hagari, a military spokesman, told reporters that the raid had uncovered weapons, a laptop computer and other items he said signaled a Hamas presence at the hospital. A video released by the military showed around a dozen guns, some grenades and ammunition, and tactical gear such as body armor and backpacks. The military did not present evidence of tunnels or a command center.

The Post could not independently verify the claims.

The Gaza Health Ministry said it received a warning from the IDF shortly before the operation, which many had predicted. Israel had said Hamas activity at the hospital was a top target in its war against the militants who carried out a deadly surprise attack in southern Israel last month. More than 1,200 Israelis were killed in the Oct. 7 attack, triggering Israel’s response. More than 11,000 Palestinians in Gaza have been killed in the ensuing air and ground war, according to the Gaza Health Ministry. The ministry said last week it could no longer feasibly count the dead.

A satellite image captured by Planet Labs on Tuesday at 1:45 p.m. local time showed Israeli troops gathered at several locations near al-Shifa Hospital not long before their raid on the hospital began. The Israeli military said its “precise and targeted operation against Hamas” began around 2 a.m. local time Wednesday.

By Wednesday evening, Israeli tanks had pulled back from the hospital but soldiers remained in the complex, the IDF said in a statement. Gaza hospitals chief Munir al-Bursh, reached by telephone inside the hospital, confirmed the ongoing presence of Israeli troops. Israeli forces were stationed in four buildings in the hospital complex, he said, while dozens of tanks remained by the entrance.

“They called me and asked me to come down to meet the commander but I refused and told them you can come to arrest me but I’m not coming,” Bursh said. He said medical facilities were damaged, two mechanical engineers were arrested and some medical staff were subjected to strip searches.

Omar Zaqout, head of al-Shifa’s emergency department, told Al Jazeera that the hospital had endured a night of nonstop gunfire and explosions before Israeli forces “blasted” into the compound, sending shrapnel into buildings where patients and displaced families were sheltering.

The near-blackout conditions allowed only a partial, murky look at what was going on inside the compound. Phone numbers for many medical staff were disconnected or rang unanswered. Plastic surgeon Ahmed al-Mokhallalati told The Post he was hiding with 15 colleagues in the hospital’s main surgical building. His summary: “We are surviving.”

The complex includes separate buildings for different medical specializations. The scene was so dangerous and communications so weak, Mokhallalati said, that doctors holed up in one building had no idea what was going on in the others. “We are not moving around in the building,” he said. “It’s totally risky to move between buildings or look through the window, as there are snipers and someone could shoot you.”

Mokhallalati said soldiers faced “no resistance at all.” He said he had never seen an armed fighter with Hamas or any other group in the hospital. “I and my colleagues would not put our lives at risk because someone with a gun is around,” he said. “There are only civilians here.”

The Israeli military said troops “encountered explosives and terrorist squads” while battling their way into al-Shifa and killed five militants. Bursh, the Gaza hospitals director, said Israeli soldiers had fanned out to search the compound.

By midday, there was no sign that any of the more than 240 Israeli hostages seized by Hamas and its allies on Oct. 7 had been found at the site, according to Israeli Army Radio, a military-run outlet. “No friction has been recorded so far between the troops and any of the patients or medical staff,” the report said.

Locating hostages wasn’t the main objective of the hospital raid, an IDF international spokesman told CNN. Israeli Lt. Col. Richard Hecht told the channel the focus was on “intelligence and dismantling certain capabilities that we had intelligence on.”

Sara Netanyahu, the wife of Israeli Prime Minister Benjamin Netanyahu, wrote to first lady Jill Biden on Wednesday requesting help freeing Israeli abductees in Gaza. In the letter, she confirmed for the first time that one of the hostages had given birth in captivity.

Sara Netanyahu sought to invoke a maternal bond, writing of 32 children among the hostages, and asked Biden to “speak out” on their behalf. She referred to a pregnant captive who had given birth and asked Biden to “imagine, as I do, what must be going through that young mother’s mind as she is being held with her newborn by these murderers.”

Later Wednesday, a video recording posted by Reuters showed thick smoke wafting through one section of the hospital as medical workers wheezed and coughed. Some pulled scrubs and masks over their mouths as they moved through damaged hallways. The recording showed patients, including one who appeared to be a child, being wheeled on stretchers through clouds of smoke.

Gaza Health Ministry spokesman Ashraf al-Qudra said Tuesday that no ambulances had been allowed to reach the hospital since Friday. Around 700 patients, more than 400 health workers and around 3,000 displaced people were at the compound, the WHO said Tuesday.

Israeli and U.S. intelligence allege that Hamas operates a subterranean command center at the complex, using the injured and displaced as human shields.

Qudra, speaking on a choppy line from the complex early Wednesday, told The Post that only civilians were at the hospital. He rejected claims to the contrary.

Alyona Synenko, a spokeswoman for the International Committee of the Red Cross, told The Post that the aid group had received many calls from people inside the hospital asking for help to evacuate. She said the ICRC could not safely coordinate their movement. People calling “say if they open the door they risk being shot, as the fighting has been relentless,” she said.

Al-Shifa and other Palestinian medical facilities are struggling under increasingly grave conditions, overwhelmed by casualties and hampered by the lack of basic services. More than half of the hospitals in Gaza are no longer functional, the WHO has said.

A fuel tanker entered Gaza via the Rafah border crossing with Egypt on Wednesday for the first time since the war began. Thomas White, the Gaza director for UNRWA, the U.N. agency for Palestinian refugees, confirmed on social media that the organization had received about 23,000 liters of fuel from Egypt, “restricted by Israeli authorities” to be used only for vehicles to transport aid. It could not be used for water systems or hospitals.

The one-time delivery amounted to “only 9% of what we need daily to sustain lifesaving activities,” White said. Until Wednesday, Israel had refused to allow fuel into Gaza, saying Hamas and other armed groups could divert it for military purposes, U.N. authorities said.

UNRWA head Philippe Lazzarini said the single shipment, with the restrictions on its use, was inadequate to the need. “Fuel for trucks only will not save lives anymore,” he said. “Waiting longer will cost lives. Much more fuel is needed. . . . It is appalling that fuel continues to be used as a weapon of war.”

Ishaq Sidr, the Palestinian minister of communications and information technology, said the entire Gaza Strip could go incommunicado within the next 24 hours as a result of fuel shortages to power cell and internet lines. “We are close to completely stopping the provision of all communications services unless the necessary fuel is secured,” he said.

“Cutting off communications means cutting off all distress messages from Gaza,” he said. There will be “no coverage of all the destruction.”

Dadouch reported from Beirut, Allam from Cairo and Harb from London. Adela Suliman in London and Hazem Balousha in Amman, Jordan, contributed to this report.

previous coverage

• Hamas agrees to tentative deal to free dozens of hostages, pending Israel’s approval