A power outage originating in Arizona and extending to Southern California and parts of northern Mexico left several million people without electricity Thursday and Friday.
By midnight, power had been restored in parts of Orange and San Diego counties, and full service resumed Friday morning, officials said.
San Diego Gas & Electric's president, who has been with the utility since 1971, said he'd never seen anything like Thursday's outage.
"We want everybody to be safe," an SDG&E spokesperson said at an 8 p.m. news conference from San Diego County's emergency center. "We have deployed all our crews into the field to switch the circuits back on. Again, slow process. It's going to take a while. But the system restoration has started."
Nevertheless, the Capistrano Unified School District announced it would close all of its schools Friday.
The outage was triggered by an Arizona utility employee working at a substation northeast of Yuma, Ariz. That caused a 500-kilovolt high-voltage line from Arizona to California to trip out of service, knocking out power to all of SDG&E's customers, disrupting cell phone service and snarling roads as traffic signals went dark.
At about 5 p.m., the San Onofre nuclear power plant announced it was shutting down because of the power outage, although officials said it was a routine procedure and presented no danger.
Patch's coverage will be updated below.
2:45 a.m. Friday
If they wake up in the middle of the night and flip a light switch, nearly half of SDG&E's customers will no longer find themselves in the dark.
1 a.m. Friday
About a third of SDG&E's 1.4 million customers now have their power back, the utility said.
12:05 a.m. Friday
Power restored in Laguna Niguel, Dana Point and parts of Mission Viejo and San Clemente, according to SDG&E.
6 p.m. Thursday
A California utilities organization called the Independent System Operator Corp. identified a broken major power conduit as the culprit in the massive blackout.
A 500-kilovolt high-voltage line from Arizona to Southern California tripped out of service, according to a release from Southern California Edison.
Much of Southern California’s electricity flows from out-of-state plants, and the failure of the high-voltage line cut most of the imported power to that part of the state.
The Independent System Operator Corp., set up after the rolling blackouts in California in the 1990s, is sort of a traffic controller for the electrical grid in the state, making sure energy flows efficiently over the lines, although individual utility companies still own the equipment. It is also involved in identifying the source of power outages.
In Laguna Beach, traffic signals are working.
In Mission Viejo, the library announced an early closing, at 6:30 p.m.
5 p.m. Thursday
Gil Alexander, Southern California Edison spokesman for the , released this statement:
"Edison is working with the California Independent System Operator to determine grid factors that caused the two San Onofre units to trip offline as designed at 3:38 p.m.
"The shutdown process is proceeding safely and poses no danger to workers or the public. Offsite power is available for the plant’s safety systems.
"Edison is aware of grid-related outages in sections of Orange and Riverside Counties."
In Mission Viejo, Saddleback College canceled classes Thursday evening, said spokesperson Amy Wheeler.
Mayor Dave Leckness was at the city's water reclamation plant shooting a video when the power went off.
"All the backup and emergency pumps are working flawlessly," he said. "Every single one of them is on now. It's great to see what happens in an emergency here. It went off without a hitch."
The mayor also said the La Paz/Marguerite intersection is without power, as is the Crown Valley/Marguerite intersection. But the Oso/Marguerite intersection is working fine.
4:45 p.m. Thursday
San Juan Capistrano's utilities department is activating its emergency generators. However, the backup power in City Hall is out. City staffers are out setting up stop signs at the major intersections because traffic signals are also out.
The Orange County Fire Authority, through Twitter, urged residents to check on the elderly, pets, children and neighbors.
There are no traffic lights in South Laguna, either.
Metrolink officials warn passengers to expect delays as a result of the outage.
4:30 p.m. Thursday
4:15 p.m. Thursday
Power is out throughout San Clemente, San Juan Capistrano, Laguna Niguel, Dana Point, parts of Mission Viejo.
Other users said power is out in San Diego County south through Chula Vista.
The SDG&E website is also down.
4 p.m. Thursday
The following was tweeted by @SDG&E:
"We understand power is out, we are working on the cause and solution. We do not have a restoration time yet."
Jenna Chandler, Sarah Decrescenzo, Rich Kane and Peter Schelden contributed to this report.
EDITOR'S NOTE: Because of incorrect information from another media source, some outage locations were misidentified in an earlier version of this article. Patch regrets the error.