Two stations on Metro's Blue and Yellow lines reopened Monday after the stations were briefly shuttered for unscheduled track work.
Metro has not yet said what prompted the closure, but Twitter users shared photos and videos of a fire on the tracks.
The Crystal City and Pentagon City stations were closed about 10 a.m., Metro said.
Metro has not confirmed the cause of the closure, but photos from riders show a small fire on the tracks at Pentagon City.
No trains are operating between the National Airport and Pentagon stations at this time. The Yellow Line is operating between Huntington and National Airport while the Blue Line is only running between the Franconia and National Airport stations, and the Pentagon and Largo stations.
Bus shuttles are available.