SAN JOSE (CBS SF) — A large and widespread power outage affected 21,663 PG&E customers in the South Bay, according to PG&E.

The outage was reported at 7:27 p.m. Sunday evening. Customers immediately lost power.

PG&E did not immediately know the cause of the outage but said they are investigating the cause. Crews assessed power lines and poles to find the root of the outage.

At around 10 p.m., the utility said they believed there was some sort of equipment issue at the Saratoga substation. Power was restored to the afflicted area at around 10:30 p.m.

Some of the affected areas included the cities of Campbell, Saratoga and West San Jose and Los Gatos.

The total duration of the outage was just over three hours.