The delays began at 6:12 a.m. when an outage occurred in Berkeley, affecting trains headed from Richmond to Daly City and Fremont.
Then, a second outage in Richmond created a switching problem at BART's Richmond maintenance yard, Allison said.
"We are having trouble getting trains out of that yard and into the system," Allison said at about 7 a.m.
As a result, delays of up to 30 minutes are reported on those two lines. BART's other lines are not affected.