Bay Area Rapid Transit has resumed all operations Saturday morning after hours of complete shutdown due to a computer problem.
All BART were reopened around 11 a.m., according to BART.
A computer problem that deadlocked service was caused overnight when BART experienced a computer network failure. It occurred as crews working on BART's uninterruptible power supply in Oakland ran but the maintenance work wasn't related to the power failure, Stalter said.
Both the computer and power supply systems are necessary for BART to safely operate trains, according to officials, as traction power moves the trains and the routing systems ensures they are traveling to an appropriate destination.
"BART will perform a comprehensive forensic evaluation to determine exactly what happened to cause the network failure. This analysis is expect to take several days due to the complexities of our system," the agency said in a statement.
Bus agencies that run parallel service to BART stations provided riders free trips while the system was down.
There is no estimated time of when service would be restored and commuters are advised to seek alternate routes of transportation as crews work to repair the issue.
BART advised travelers to use its trip planner at bart.gov to find transit options.