A humanitarian catastrophe loomed on the Gaza Strip as the blockaded coastal strip ran dangerously low on food and water on Monday amid intensifying Israeli airstrikes.

More than a million people have already fled their homes ahead of an expected Israeli ground invasion targeting the Hamas resistance group.

As the enclave’s food, water and medicine supplies dwindled, all eyes were on the Rafah crossing between Gaza and Egypt, where trucks carrying badly needed aid have been waiting for days as mediators press for a cease-fire that would allow them enter Gaza and allow foreigners to leave. Rafah, Gaza's only connection to Egypt, was shut down nearly a week ago because of Israeli airstrikes.

Egypt's Foreign Minister Sameh Shoukry said Israel "has not taken a position to open the crossing from the Gaza side." The Israeli government also denied reaching any such arrangement.

Hundreds of thousands of Palestinians sheltering in U.N. facilities are on less than 1 liter (1 quart) of water per day. Hospitals warn they are on the verge of collapse, with emergency generators that power machines like ventilators and incubators down to about one day of fuel and supplies of medicine almost exhausted.

The Gaza Health Ministry said 2,750 Palestinians have been killed and 9,700 wounded since the fighting erupted, more than in the 2014 Gaza war, which lasted over six weeks. That makes this the deadliest of the five Gaza wars for both sides.

Nearly 1,400 Israelis have reportedly died in the surprise Hamas incursion on Oct. 7. The Israeli military said Monday that at least 199 hostages were taken back in Gaza, higher than previous estimates. The military did not specify whether that the number includes foreigners.

Israeli airstrikes have pulverized entire neighborhoods as Palestinian groups fired sporadic rockets into Israel. Israel is widely expected to launch a ground offensive against Hamas leaders and infrastructure but street-by-street fighting would likely cause mounting casualties on both sides.

Israel has ordered more than 1 million Palestinians – almost half the territory’s population – to leave Gaza City and the surrounding area for the enclave's south. The military says it is trying to clear away civilians ahead of a major campaign against Hamas in the north. Hamas, however, has urged people to stay in their homes so as not to cause a second Nakba or mass displacement.

For a third day, Israel announced a "safe corridor" for people to move from north to south between 8 a.m. and noon. It said more than 600,000 people have already evacuated the Gaza City area.

Hospitals at breaking point

Hospitals in Gaza are expected to run out of generator fuel in the next 24 hours, endangering the lives of thousands of patients, according to the U.N. Gaza's sole power plant shut down for lack of fuel after Israel completely sealed off the 40-kilometer (25-mile) long territory.

The World Health Organization (WHO) said hospitals are "overflowing" as people seek safety. "We are concerned about disease outbreaks due to mass displacement and poor water and sanitation," it said.

Four hospitals in northern Gaza are no longer functioning and 21 have received Israeli orders to evacuate. Doctors have refused, saying it would mean death for critically ill patients and newborns on ventilators.

The WHO said water shortages caused by Israel's decision to cut off water supplies, combined with a lack of fuel for pumps and desalination stations, put thousands of hospital patients at risk.

"Water is needed to ensure sanitary conditions on inpatient wards, in operation rooms, and in emergency departments. It is essential for the prevention of hospital-associated infections and for the prevention of outbreaks in hospitals," the WHO said.

The U.N. health agency said life-saving assistance for 300,000 patients is currently awaiting entry through Rafah. On the Gaza side, crowds of Palestinians with dual citizenship waited anxiously, sitting on suitcases or crouched on the floor, some comforting crying infants.

"They are supposed to be a developed country, talking about human rights all the time," Shurouq Alkhazendar, whose two kids are American citizens, said of the United States. "You should protect your citizens first, not leave them all alone suffering and being humiliated in front of the crossing."

Over 1 million people – about half of Gaza's population – have left their homes in a little over a week. Some headed to the south, while tens of thousands are still sheltering in hospitals and U.N. facilities in the north, according to the U.N. Travel within Gaza is difficult and dangerous, with roads destroyed and Israel offering only short windows for civilians to travel without the threat of strikes.

The U.N. agency for Palestinian refugees said it has been forced to ration water in schools and other facilities that have been turned into shelters, giving people just 1 liter (1 quart) a day to cover all their needs.

Israel has said the siege won’t be lifted until all the captives are released, but the country's Water Ministry said water had been restored at one "specific point" in Gaza, at a location outside the southern town of Khan Younis. Aid workers in Gaza said they had not yet seen evidence the water was back.