Electrical equipment failed Thursday night, leaving 7,500 Pacific Gas & Electric Co. customers in the Mission, Twin Peaks, Noe Valley and Portola neighborhoods without power for several hours, according to PG&E.

The reasons for the equipment and subsequent power failure are unknown.

The outage began at 7:47 p.m., and by 9 p.m. more than 7,300 of the affected customers had their power back, according to PG&E. The remaining customers had electricity back by 1 a.m. Friday morning, according to the energy company.