The Federal Transit Administration is investigating the fire and smoke emergency that shut down a portion of Metro's Red Line for several hours on Saturday.
A Metro spokesperson confirmed to WTOP the FTA is investigating the incident.
WTOP reports Metro does not know the exact cause of the smoke and fire, but spokesperson Richard Jordan said an electrical arcing insulator was the likely cause.
Red Line service was suspended between the the Van Ness and Medical Center stations after a train going toward the Friendship Heights station was forced to reverse toward the Tenleytown-AU station due to smoke.
No one was injured, Metro and fire officials said.