A power outage in San Francisco Friday affected about 90,000 customers, from the Financial District to the Presidio, according to the San Francisco of Department of Emergency Management. The outage -- likely caused by a fire at a PG&E substation -- started around 9 a.m.

As of 3:30 p.m., only about 3,000 customers were without power, according to PG&E, and it was fully restored a little after 5 p.m.

A circuit breaker failed at a Pacific Gas and Electric substation at Larkin and Eddy streets, causing an electrical fire. At 9:30 a.m. San Francisco emergency dispatchers were notified that there was a fire at the substation, according to San Francisco Fire Department Chief Joanne Hayes-White. Insulation at the substation caught fire, and continued to reignite until the Fire Department could bring a carbon dioxide unit to help put out the blaze.

PG&E Vice President of Electric Distribution Barry D. Anderson said earlier that the utility was aiming to restore power to all customers by 5 p.m.

No one was harmed in the fire and there was limited damage to the electrical facilities, according to PG&E spokesman Donald Cutler.