Power has been restored to 1.4 million customers as the system recovers from a major outage that affected a wide area of Southern California.
Outage Updates From SDG&E | Power Conservation
"It does not appear there was an overload," said David Feier of SDG&E. "An investigation will show what happened."
The outage was accidentally triggered at about 4 p.m. Thursday when an electrical worker removed a piece of monitoring equipment at a power substation in southwest Arizona, officials at Phoenix-based Arizona Public Service Co. told the Associated Press. It was not clear why the mistake led to such a widespread problem.
"This was not a deliberate act. The employee was just switching out a piece of equipment that was problematic,'' said Daniel Froetscher, an APS vice president.
The utility made the announcement that power had returned to a large swath of the region at about 5 a.m., meaning some people probably awoke Friday to find their power had been restored.
Some customers might not have power until Saturday, according to SDG&E. The utility said anyone who is still without power can call 800-411-7343.
Local news from across Southern California
Schools will be closed Friday in the Capistrano Unified School District. San Diego State University also canceled classes.
The outage extended into southern Orange County, across California's inland deserts, as far east as Yuma, Ariz., and into Mexico. The region is home to some 6 million people.
At Desert Springs Health Care nursing home in Indio, more than 60 people were evacuated when a backup generator failed. Power was restored at about 9:30 p.m. after 21 people were relocated.
Tens of thousands of customers were without power in Riverside County. Power was restored to all of the Imperial Irrigation District's 150,000 customers by midnight.
The outage left residents and businesses without air conditioning and caused major backups for motorists. Power was restored to different parts of the region throughout the ovenight.
Commuters also faced a shutdown of the trolley system that shuttles thousands of commuters every day in San Diego. Trains were stopped in Los Angeles, an Amtrak spokesman said, because there was no power to run the lights, gates, bells and traffic control signals.
The outage didn't stop the party at some restaurants and bars in San Diego's Gaslamp District.