A section of track lost power at 4:42 a.m., and the first trains of the morning commute had to single-track between Daly City and 24th Street, BART spokesman Jim Allison said.
Allison said the outage was caused by a faulty relay in a piece of electrical equipment. BART crews have repaired the problem and trains resumed normal service at 6:52 a.m.
As of 7:20 a.m., there were residual delays of up to 15 minutes to trains heading in and out of San Francisco, Allison said.
