BART officials say the Fremont line was resuming normal service as of 7:59 p.m. after experiencing major delays due to equipment issues Thursday evening.
There was no train service for some time at the Union City station after someone reported sparking behind the train. Firefighters and technicians responded to the scene at around 7:15 p.m.
Officials said upon arrival there was not fire, but only a smoldering drum brake from a train.
The train is disabled and no one is on the train, BART officials said. The delay affected the Fremont line in the Warm Springs and Richmond directions because of the problem.
Travelers were advised to take Alameda-Contra Costa Transit District buses to get around Union City station. BART officials said to use bus lines 97, 99, 200 or 217.
Video and photos were posted on social media showing long lines of people waiting for buses and of firefighters using a ladder to reach the train from below.
Check with BART.gov on the latest alerts and advisories.
KTVU contributed to this report