The outage was reported shortly before 4 p.m. and is affecting 1,150 customers, spokeswoman Tamar Sarkissian said.
Trains are running through the Downtown Berkeley station but are not stopping there, according to a Bart employee.
The closure has caused delays for trains heading in the Fremont, Richmond, Millbrae and San Francisco directions, according to BART.
No estimated time was available for when power would be restored.
