PORTLAND, Ore. — An Oregon-bound United Airlines flight from Washington, D.C., that was diverted to Chicago for security concerns landed early this morning in Portland.

United spokesman Rahsaan Johnson told reporters that passengers on Flight 251 from Dulles International Airport were taken off at O’Hare International Airport on Tuesday evening and rescreened through security.

He says two or three passengers who had not been following crew instructions were not on board the plane when it continued to Portland International Airport. Johnson says he couldn’t say whether they were detained.

He says another passenger was ill, which may have complicated the situation on the plane.

It wasn’t immediately clear how many passengers were aboard.