"I mean I needed to get to the post office by 7 o'clock and now I can't get there," said Kathy Cho, a BART passenger.
Eastbound trains were stopped in the Transbay Tube and rolled back to San Francisco on the same track.
After leaving the tube and heading to West Oakland at close to 70 mph, BART says a piece of the undercarriage fell off. That metal touched the third rail which caused arcing and a lot of sparks according to a passenger on that train.
"Between the loud noise, the feeling of hitting something, and the sparks it caught everybody's attention on the train. Everyone gasped and then went silent and we all knew something had happened," said Beth Pramme, a BART passenger.
So many people filled the Embaradero platform, many passengers were held behind the upstairs gates. This is the fourth recent hassle for BART passengers, including two strikes and last Friday's computer glitch.
"I think this is irritating because BART always has some type of issue happening. If you think back a couple of weeks ago, we had the strike which inconvenienced a whole bunch of people and now this," said Damon Whitaker, a BART passenger.
All trains were running again just after 7 p.m. Tuesday.