Update at 4:45 p.m. — No signs of smoke have been found. Firefighters on the scene say that the smoke is believed to be from a train that has since traveled into the District.
For the third time in a week, Arlington County firefighters are responding to the Rosslyn Metro station for a report of smoke in the tunnel between Rosslyn and Foggy Bottom.
D.C. firefighters are also responding to the Foggy Bottom station.
Twice this past weekend, firefighters responded to the station but found no sign of smoke.