The San Francisco-bound train stopped around 8:15 a.m. Wednesday in the Berkeley hills between the Orinda and Rockridge stations when a brake became engaged. BART spokeswoman Alicia Trost told KTVU-TV the train emitted white smoke, and some people felt sick.
Another BART spokeswoman, Luna Salaver, said at least two passengers experienced medical emergencies, including one who suffered an asthma attack.
BART was warning commuters to expect significant delays.
Salaver says a technician was able to release the broken brake around 9:30 a.m., and the disabled train moved on its own power to the Rockridge station in Oakland, where the 600 to 700 passengers on board were evacuated.