SAN FRANCISCO, CALIFORNIA - More than 9,000 homes and businesses in San Francisco were plunged into darkness on Wednesday night when equipment in an underground Pacific Gas & Electric Co. vault caught fire.

Workers from at least two blue PG&E trucks were examining an electrical transformer, which onlookers had said popped earlier in the night, reports SF Chronicle.

The outage affected PG&E customers in the Hayes Valley and Haight-Ashbury areas and blacked out the War Memorial Opera House during a performance of the San Francisco Ballet.

All customers impacted by the outage had their power restored later in the evening.

Source: San Francisco Chronicle