Five US Airways crew members aboard a flight from Washington were taken to a hospital Monday after suddenly becoming ill.

The crew and passengers had complained about a sulfur-type odor after the flight left Ronald Reagan-Washington National Airport, so the flight returned to the airport and the plane was swapped out for another.

Five crew members still became ill with unspecified symptoms during the flight, according to Valerie Wunder, a spokeswoman for US Airways, based in Phoenix. The crew members were taken to a local hospital for treatment after the flight landed in Boston.

None of the 81 passengers on Flight 2022 was affected, she said.