Metro is investigating a fire that broke out under the third car of a Red Line train heading to the Forest Glen station.
Spokeswoman Caroline Lukas says it did not appear to be the result of anything "nefarious."
Thousands of passengers were stranded while firefighters put out the smoky fire on the train stopped at the Silver Spring station. Metro put a bus shuttle in place to help passengers who were stuck without transportation.
A spokesman for Montgomery County Fire and Rescue tells FOX 5 the problem seemed to involve the collector shoe that kicks power up to the train from the track. Spokesperson Scott Graham says that sometimes sparks small fires that can create a lot of smoke.
Back in January, a smoky track problem caused another rush hour meltdown. That was an arcing insulator on a track on the Green line. Lots of passengers evacuated themselves and walked through the tunnel to the Anacostia station to get out.
Metro says it is conducting an investigation to get to the bottom of the Red Line fire.