The World Health Organization described Gaza’s al-Shifa hospital as a “death zone,” after a U.N. team visited the largest medical complex in the Palestinian enclave on Saturday.

“The team saw a hospital no longer able to function: no water, no food, no electricity, no fuel, medical supplies depleted,” WHO’s director general, Tedros Adhanom Ghebreyesus, wrote on social media. 

He announced WHO was trying to set up an urgent evacuation plan from the current situation, which was described as “unbearable and unjustifiable,” and called for a cease-fire. 

Some 290 patients, including 32 babies in extremely critical condition, were left at al-Shifa, according to the U.N.-led mission, which accessed the facility briefly. The team also saw a mass grave at the entrance of the hospital, it said.

Meanwhile, the White House said the U.S. was working “hard” to get a deal between Israel and Hamas that would see the release of hostages seized by the militant group in exchange for a five-day pause in the fighting, after the Washington Post reported that the two sides are close to agreement on a U.S.-brokered deal. Israeli Prime Minister Benjamin Netanyahu and U.S. officials said no deal had been reached yet.

More than 11,500 Palestinians have been killed, while another 2,700 have been reported missing, according to Hamas-run health authorities in the Gaza Strip, following the group’s attack into southern Israel six weeks ago, which triggered the war. The count does not differentiate between civilians and combatants.

Around 1,200 people have been killed on the Israeli side, mainly civilians from Hamas’ attack, in which the group also took 240 hostages back into Gaza.

Israel has repeatedly said the al-Shifa hospital houses a Hamas command center and announced it would soon release photos of the military’s findings of the hospital which include a tunnel shaft, Israel’s spokesman Daniel Hagari said during a news conference Saturday evening.