American Eagle spokesman Tim Smith says Flight 4117 landed safely with 45 passengers aboard around 11:50 p.m. Monday.
Smith said when the crew was notified of a security concern during the flight and air traffic controllers advised them to land at Dulles, in northern Virginia, instead of Reagan. Smith said he could not get into the details about what the security concern was.
TSA spokeswoman Andrea McCauley said the agency was notified of an "passenger acting unusually" on board. McCauley said law enforcement cleared all of the passengers after the plane landed, and they were allowed to proceed.
Smith said most passengers left the airport on their own, while others were offered ground transportation to Reagan National Airport, their planned destination.