Power was restored to more than 10,700 customers in the Whittier area who were in the dark for hours Monday evening, according to Southern California Edison.
The utility said the outage began shortly before 7 p.m. Electricity was restored at about 9:30 p.m.
A fire at the Murphy Substation is being blamed for the massive outage, according to the Los Angeles City Fire Department, though SoCal Edison officials would not say what cut the power to thousands of customers.
"There was fire from the oil that is within the transformers," said LA County Fire Captain Frank Garrido. "When the transformer did blow, the oil came out and onto the ground and was just burning the area around it.
The blaze was extinguished with dry chem extinguishers, Garrido said.
At the height of the blackout, some 10,781 customers were in the dark.
NBC4's Robert Kovacik contributed to this report.