According to an SFFD dispatcher, crews responded to reports of an explosion and a small amount of smoke around 1:45 p.m. Sunday.
BART says they closed the Civic Center station after a train experienced a brake overload. Crews checked the tracks and removed the train that experienced the mechanical problem. Normal service has been restored at the station, though commuters should still expect delays in both directions.
In addition to major BART delays, San Francisco Municipal Railway service was also temporarily disrupted Sunday afternoon.
There were no immediate reports of any injuries.
Stay with ABC7 News for the latest details on this developing story.
(Bay City News contributed to this story)