Initially, the train service was down across the entire system due to a power problem that led to a series of computer problems.
In a 9:03 a.m. update, BART reported limited service is restored. Just before 11 a.m., the system resumed normal service.
"BART crews working overnight on BART's uninterruptible power supply in Oakland ran into problems that impacted our traction power supply system and train control routing system," wrote the agency in an online statement.
"Without both these systems, we are not able to safely dispatch trains for service."
According to the online post, traction power sends power to trains and the routing system is how they control which direction and route the trains take.
For safety purposes, a series of test trains were deployed before allowing riders onboard.
While waiting for service restoration, some riders were getting frustrated.
Sheeva, for example, says she waited at the Walnut Creek Station for nearly two hours.
For others, it was close to three.
BART suggests riders can use their Trip Planner at bart.gov and their official app to plan trips and stay on top of alerts.