Some hospitals in the U.S. are without essential staff because international doctors who were set to start their medical training this week were delayed by the Trump administration’s travel and visa restrictions.

It’s unclear exactly how many foreign medical residents were unable to start their assignments, but six medical residents interviewed by The Associated Press say they’ve undergone years of training and work only to be stopped at the finish line by what is usually a procedural step.

“I don’t want to give up,” said a permanent Canadian resident who matched to the University of Pittsburgh Medical Center Harrisburg but had her visa denied because she is a citizen of Afghanistan. She requested to remain anonymous for fear of reprisal. “But the situation also seems so helpless.”