Nearly 90,000 customers were without electricity starting shortly before 6 a.m. in Hermosa Beach, Redondo Beach, Hawthorne, Gardena and Torrance, said Robert Villegas with Southern California Edison.
About 25,000 customers got their power back within a half-hour and it was restored to the remainder by about 7 a.m., he said.
The cause of the power loss was under investigation.
A major oil refinery run by PBF Energy in Torrance began burning off its product in response to the outage. A huge flare could be seen for many miles, and residents near the refinery were briefly urged to close their windows and turn off fans because of resulting smoke.
Refineries typically respond to outages by burning off product to relieve pressure and ensure gases are safely combusted.
A message seeking information from PBF Energy on the outage's impact on the refinery wasn't immediately returned Tuesday.
The refinery, which PBF bought from Exxon Mobil in July, was briefly shut down last month following a power outage affecting more than 57,000 SoCal Edison customers in Los Angeles County.
That outage was enough to cut production temporarily at the Torrance refinery, and PBF officials said at the time it would take several days to return the plant to full service.
An explosion at the refinery in February 2015 caused it to operate at less than 20 percent capacity for months during repairs. That lengthy process sent gasoline prices in Southern California to as much as $1.50 per gallon above the rest of the nation, more than twice the usual gap, according to the Los Angeles Times.
Torrance produces 10 percent of the state's refined capacity and 20 percent of Southern California's.