But they have brought no relief to millions of Sudanese caught in the crossfire, struggling to find food, shelter and medical care as explosions, gunfire and looters wreck their neighborhoods. In a country where a third of the population of 46 million already needed humanitarian assistance, multiple aid agencies have had to suspend operations and dozens of hospitals have been forced to shut down. The U.N. refugee agency said it was gearing up for potentially tens of thousands of people fleeing into neighboring countries.

Calls for negotiations to end the crisis in Africa’s third-largest nation have been ignored. For many Sudanese, the departure of diplomats, aid workers and other foreigners and the closure of embassies are terrifying signs that international powers expect the mayhem to only worsen.

Thousands of Sudanese have been fleeing Khartoum and its neighboring city of Omdurman. Bus stations in the capital were packed Tuesday morning with people who had spent the night there in hopes of getting on a departing bus.

Drivers increased prices, sometimes tenfold, for routes to the border crossing with Egypt or the eastern Red Sea city of Port Sudan. Fuel prices have skyrocketed, to $67 a gallon from $4.20, and prices for food and water have doubled in many cases, the Norwegian Refugee Council said.

Those lucky enough to reach the border crossings face additional hardships.

Moaz al-Ser, a teacher, arrived at the Arqin border crossing with Egypt early Tuesday with his wife and three children after a harrowing trip from Omdurman. They were among hundreds of families who were waiting to be processed. Many had spent the night in an open area near the border.

“The crossing point is overwhelmed and authorities on both sides don’t have the capacity to handle such a growing number of arrivals,” he said.

The new 72-hour cease-fire, announced by U.S. Secretary of State Antony Blinken was to last until late Thursday night, extending a nominal three-day truce over the weekend.

The Sudanese military, commanded by Gen. Abdel Fattah Burhan, and the rival Rapid Support Forces, a paramilitary group led by Gen. Mohammed Hamdan Dagalo, said Tuesday they would observe the cease-fire. In separate announcements, they said Saudi Arabia played a role in the negotiations.

But fighting continued, with explosions, gunfire and the roar of warplanes overhead around the capital region.

“They stop only when they run out of ammunition,” Omdurman resident Amin Ishaq said. Al-Roumy, a medical facility in Omdurman, said it suspended its services after it was hit by a shell Tuesday.

“They don’t respect cease-fires,” said Atiya Abdalla Atiya, a senior figure in the Sudan Doctors’ Syndicate, a group that monitors casualties.

Dr. Bushra Ibnauf Sulieman, a Sudanese-American physician who headed the Faculty of Medicine at the University of Khartoum, was stabbed to death outside his home, the Doctors’ Syndicate said. He had practiced medicine for many years in the United States, where his children reside, but had returned to Sudan to train doctors. Colleagues said he had been treating those wounded in the fighting in recent days and that it was not known who killed him.

The World Heath Agency meanwhile expressed concern that one of the warring parties had seized control of the central public health laboratory in Khartoum.

“That is extremely, extremely dangerous because we have polio isolates in the lab. We have measles isolates in the lab. We have cholera isolates in the lab,” Dr. Nima Saeed Abid, the WHO representative in Sudan, told a U.N. briefing in Geneva by video call from Port Sudan.

He did not identify which side held the facility but said they had expelled technicians and power was cut, so it was not possible to properly manage the biological materials. “There is a huge biological risk.”

Clashes meanwhile escalated in the western Darfur region, residents said. Armed groups, wearing RSF uniforms, attacked several areas in Genena, a provincial capital, burning and looting properties and camps for displaced people.

“Fierce battles are raging all over the city,” said a doctor in Genena, who asked to remain anonymous for fear of reprisals. “All eyes are on Khartoum but the situation here is unimaginable.”

Women and children were fleeing homes in the city center, and the city’s main hospital has not functioned for days, with unknown numbers of dead and wounded, she said.

More fighters on motorcycles and horses have flowed into the city to join the battles, with dead bodies lying in the streets, according to Darfur 24, an online news outlet focusing on covering the war-wrecked region.

The RSF has its roots in Darfur, where it emerged from the notorious Janjaweed militias that committed atrocities there while putting down a rebellion in the 2000s.

At least 459 people, including civilians and fighters, have been killed, and over 4,000 wounded since fighting began, the U.N. health agency said, citing Sudan’s Health Ministry. Among them were 166 deaths and over 2,300 wounded in Khartoum, it said.

Those who are able have made their way to the Egyptian border, Port Sudan or relatively calmer provinces along the Nile. But the full scale of displacement has been difficult to measure.

Mohammed Mahdi, of the International Rescue Committee, warned that resources were growing thin at the Tunaydbah refugee camp in eastern Sudan after 3,000 people fleeing Khartoum took refuge there, joining some 28,000 refugees from Ethiopia.

At least 20,000 people have fled from Khartoum to the city of Wad Madani, 160 kilometers (100 miles) to the south, the U.N. Office for the Coordination of Humanitarian Affairs said. Some 20,000 Sudanese have fled to Chad and around 4,000 South Sudanese refugees living in Sudan have returned home, according to the U.N. refugee agency, which is gearing up for tens of thousands more to flee to neighboring countries.

Meanwhile, airlifts of foreigners continued.

Germany said its last rescue flight would take off Tuesday, having so far evacuated nearly 500 people over three days. French military spokesman Col. Pierre Gaudilliere told journalists Tuesday that the French evacuation mission was completed and had flown out more than 500 people from 40 countries, though a Navy frigate will remain off Port Sudan to help evacuations.

The European airlift, pulling out a broad range of private citizens from many countries, has stood in contrast to more limited operations by the United States and Britain, which sent in teams Sunday to extract their diplomats but initially said they couldn’t organize evacuations for private citizens.

After growing criticism of its failure to help civilians, Britain said Tuesday it conducted its first evacuation flight for U.K. private citizens from an air base near Khartoum for Cyprus, with two more flights expected overnight. Earlier, Foreign Secretary James Cleverly said those wanting to get on a flight would have to make their own way to the airfield, calling the situation “dangerous, volatile and unpredictable.”

The U.S. said Monday it is now helping to connect private American citizens to other countries’ convoys making the journey from Khartoum to Port Sudan and then to find transport out of the country. White House national security adviser Jake Sullivan said reconnaisance assets are helping to determine safe routes but that no U.S. troops are on the ground.

Associated Press writers Jill Lawless in London and Kirsten Grieshaber in Berlin contributed to this report.