Some 22,000 PG&E customers lost power in the East Bay this evening, a utility spokeswoman said.
The outage is affecting customers in Walnut Creek, Lafayette and Concord and was initially reported at around 5 p.m., spokeswoman Janna Morris said.
As of 10:20 p.m., about 130 customers remained without power.
The cause of the substation outage near Concord was not immediately known, however Morris said there have been reports of lightning strikes in the area.
No estimated time of restoration was available.
A separate outage is impacting about 1,040 customers in San Francisco's Marina District tonight, Morris said.
The cause in under investigation.