On Saturday morning, Dr. Kamal Fadlalla traveled more than two hours from his family’s home in Wad Madani, Sudan, to the country’s capital of Khartoum to board a flight back to the United States.

For Fadlalla, a second-year resident in internal medicine at Interfaith Medical Center in Brooklyn, this was to be an early ending to his first trip back to his home country since he started in his training program 20 months ago.

He left the U.S. on January 13, a week before President Donald Trump’s inauguration. Fadlalla had planned to stay in the country until early February, but colleagues called late last week to warn him to hurry if he wanted to get back into the United States. Though he had a newly issued H-1B visa for foreign workers in specialty occupations, he lived in Sudan, one of the seven predominantly Muslim countries from which President Donald Trump banned visitors for at least 90 days.

Initially, everything went fine at the airport. He received his boarding pass. He went through an immigration checkpoint and walked to his gate. But as he was about to board his Emirates airline flight, he heard his name called from the loudspeaker, instructing him to return to the counter. An officer told him the airline’s headquarters had ordered that he not board the plane. After waiting four hours at the airport, he returned to his family’s home.

“They took our boarding pass. They canceled our flight,” said Fadlalla, in a phone interview with ProPublica from Sudan. “It was really shocking for me.”

Fadlalla was turned back the same day as a first-year resident at the Cleveland Clinic was forced to leave the U.S., hours after landing at New York’s John F. Kennedy International Airport. Suha Abushamma, who is also a Sudanese citizen, was given the choice of withdrawing her visa application “voluntarily” or being forcibly deported and not allowed back to the U.S. for at least five years. Her flight back to Saudi Arabia, where her family lives, took off just minutes before a federal district judge in Brooklyn issued a stay temporarily preventing the government from deporting people like her. Ohio’s two senators, one Republican and one Democrat, have denounced her treatment.

Whether they know it or not, American patients rely on doctors trained at foreign medical schools. Each year, around a quarter of the residents and fellows in advanced training programs around the U.S. attended medical school outside the country. While some of those are U.S. citizens or permanent residents, about 15 to 20 percent of the total are not.

It is not clear how many doctors are now affected by the travel ban but the order could have devastating consequences for physicians from the seven listed countries in the weeks ahead as hospitals decide which aspiring physicians to admit to their training programs for next year. In addition to Sudan, the countries are Iraq, Iran, Yemen, Syria, Libya and Somalia.

Atul Grover, executive vice president of the Association of American Medical Colleges, said there are currently 200 to 300 applicants from the affected countries among the 35,000 people seeking residency and fellowship positions in this country. Officials are trying to figure out how the president’s executive order will affect the upcoming match process, in which interested residency programs select interested trainees.

“We have a bunch of people that are scrambling today to figure out what the deal is to hopefully let them [hospitals] know tomorrow,” Grover said. “It’s scary for people.”

When he realized he was locked out of the U.S., Fadlalla called his union and his residency program to advise them of his plight. “They’re trying to help me. They’re trying to figure out what they can do.

“My colleagues are going to be affected. My hospital is going to be affected. And for sure, my patients are going to be affected,” he said.

Fadlalla said he came to the United States several times in preparation for his residency, to take his entrance exams and for interviews. “We work very hard to get these positions,” he said. “We invest our time. It’s very expensive to travel from our home country.”

LaRay Brown, the chief executive at Interfaith hospital in Brooklyn, where Fadlalla is a resident, said she too is trying to figure out what may happen to him, and as a result, his patients. Interfaith serves a predominantly low-income patient base, many of whom have myriad health problems, drawn from the central Brooklyn communities of Bedford–Stuyvesant and Crown Heights.

“Individuals like Dr. Fadlalla are not the folks that I presume the president and others are wanting to keep the us safe from,” Brown said. “These are folks who are contributing to the country and in particular to communities that my hospital services. Like other foreign medical students from generations past, they are trying to carry out the American dream, doing good for others and in that way also trying to do good for themselves and their families.”

Fadlalla said he feels at a loss since he is now deeply rooted in the United States. “I’m sad. I’m worried. I don’t know how to plan for my life,” he said. “Everything’s there. My bank accounts are there. My house is there. My friends. I have research there. I have my patients. I have my whole life there. I’ve been working for 20 months.”

If he is kept out for 90 days, as the executive order calls for, Fadlalla said he will fall behind in his residency and may not be able to graduate on time, delaying his ability to take his board certification exams. Brown, the Interfaith CEO, said she will try to help him stay on track.

“I’m going to try very hard that it doesn’t tank his year,” Brown said. “This is not his fault. He’s stuck in the crosshairs of this unfortunate policy and we’re going to do everything we can to support him.”

Eric Scherzer, executive director of the Committee of Interns and Residents/SEIU Healthcare, a union that represents medical trainees, said his group is on the lookout for similar situations.

Scherzer noted that his union has hundreds of members who are in the United States on H-1B visas or J-1 student visas but that only a small percentage of them are from the seven nations covered by the order. As for Fadlalla, he said, the union’s lawyers are working to get him back to the U.S. but are worried. “We don’t see a clear pathway to get him back to work serving the patients that he needs to take care of in Brooklyn,” he said. “There’s tremendous amount of uncertainty.”

Fadlalla said he’s not only worried about himself but also others from his country who are applying for new residency positions, which begin on July 1. “They did their interviews. They had good scores in the exams and they’re good candidates for the match,” he said. “But they are now held in Sudan because they cannot return back to start their residency there. Everybody is worried about that.”