Repeated evacuation orders take a toll on already weakened Gazans.

An evacuation order by the Israeli military this week covering roughly a third of the Gaza Strip came as people there are less and less equipped to handle repeated forced displacements, after nearly nine months of war that have left tens of thousands dead and injured and put the territory at risk of famine.

The order, which the United Nations has estimated affects about 250,000 people, was the largest since October, when about a million residents of northern Gaza were told to flee their homes, the organization said on Tuesday.

“It’s an endless cycle of death and displacement,” said Louise Wateridge, a spokeswoman for the main U.N. agency that aids Palestinians, UNRWA, in voice messages from central Gaza on Wednesday. “People express here that they are losing hope, they are losing the willpower, faced with another forced displacement and absolutely no certainty of safety.”

On Monday the Israeli military issued the warning to leave large parts of the cities of Khan Younis and Rafah, and by Tuesday thousands of people had begun to flee. The order was followed by a night of heavy bombardment in areas of southern and central Gaza. The order came after the Israeli military said Palestinian armed groups fired a barrage of roughly 20 rockets from Gaza toward Israeli cities on Monday.

The spokesman for the U.N. secretary-general, Stéphane Dujarric, said Tuesday that his colleagues were “deeply concerned” about the impact of the order.

“People are left with the impossible choice of having to relocate — some most likely for the second or even the third time — to areas that have barely any spaces or services, or staying in areas where they know heavy fighting will take place,” he said.

The order covers more than 90 school buildings, many of which have turned into overcrowded shelters as people run out of places to stay, along with four medical facilities, Mr. Dujarric said.

Among them is the European Hospital in Khan Younis, where many were sheltering and hundreds of patients were being treated. After medical staff, patients and displaced people fled the hospital, the Israeli military said on Tuesday that it was not necessary for people to leave it.

The International Committee of the Red Cross said Wednesday that the hospital was no longer functioning because so many staff members had left.

Though many people in the evacuation zone have made the decision to flee fonce again, relocating becomes harder and harder as the war drags on.

“In terms of people’s ability to move, it’s been eight months of war, people are extremely fatigued, they’re exhausted, they’re malnourished,” Ms. Wateridge said. Health-wise, she said, “people are a lot weaker, there are more injuries, there’s been less medicine available, less fresh fruit, less water.”