PG&E is investigating a power outage that affected more than 22,000 customers in San Francisco, South San Francisco and Daly City this morning, a utility spokeswoman said.

The outage began at around 11 a.m. and disrupted power to homes and businesses in northern San Mateo County and southern San Francisco, including the Lake Merced neighborhood and the San Francisco State University campus, PG&E spokeswoman Brandi Ehlers said.

Power was restored at about 11:40 a.m., Ehlers said.

PG&E workers were still trying to determine the cause of the outage.