SAN DIEGO — More than 5 million people on both sides of the U.S.-Mexico border were left without power Thursday after a major outage that extended from Arizona to southern California, including San Diego, the eighth largest U.S. city.
The outage led to school closures, flight cancellations, blacked-out traffic lights, silent radio stations and trapped elevator passengers.
The likely culprit? An employee removing a piece of monitoring equipment that was causing problems at a power substation in southwest Arizona, officials said. The power loss should have been limited to the Yuma, Ariz., area, and Arizona Public Service was investigating why the outage wasn't contained. Dan Froetscher, a vice president at Arizona Public Service, said it wasn't a deliberate act. He would not say whether it was mistake or how much experience the employee had.
Affected were 3 million people in the San Diego area, 1.5 million in Tijuana, 1 million in Mexicali, several hundred thousand in Orange County and about 200,000 in Arizona.
"To my knowledge this is the first time we've lost an entire system," Mike Niggli, chief operating officer of San Diego Gas & Electric Co., said at a news conference.
Power was slowly coming back online for some people in Orange County, Calif., but most of the 5 million who lost electricity were expected to remain in the dark through the night.
According to the San Diego Union-Tribune, the outage began at 3:38 p.m. (7:38 p.m. EDT) when a transmission line running from Arizona to San Diego failed, triggering a cascade of events that then knocked the region's other electricity provider — the San Onofre nuclear power plant — offline.
"Essentially we have two connections to the rest of the world — one to the north and one to the east — and both of those connections were severed," Niggli said.
Charles Coleman, a spokesman from Southern California Edison, said that the two reactors at the San Onofre plant went offline as they are programmed to do when there is a disturbance in the power grid but that there was no danger to the public or to workers there.
All outgoing flights from San Diego's Lindbergh Field were grounded, and police stations were using generators to accept emergency calls across San Diego County.
San Diego's trolley system that shuttles thousands of commuters every day was shut down, and freeways were clogged at rush hour. Police directed traffic at intersections where signals stopped working.
Gas stations shut down, with no power to pump fuel and no means of processing transactions. Hospitals operated off backup power generators.
At the University of California at San Diego hospitals in Hillcrest and La Jolla, full power was being delivered to emergency rooms, burn units and other critical areas such as operating rooms that were in use when the blackout occurred, spokeswoman Kimberly Edwards told the Union-Tribune.
In Tijuana, people wandered out of their hot homes into the street to cool off while restaurants scrambled for ice to save perishable food.
About 100 elevator rescues were needed by 5:30 p.m., but Maurice Luque, spokesman for the San Diego Fire-Rescue Department, said firefighters were responding to rescues only if there was a medical emergency.
Both SeaWorld in San Diego and Legoland California in Carlsbad had to assist a few guests who were stranded on coaster rides, but the rescues were uneventful, they reported.
Residents in parts of eastern San Diego County and Yuma endured sweltering temperatures with no air conditioning.
"It feels like you're in an oven and you can't escape," said Rosa Maria Gonzales, a spokeswoman with the Imperial Irrigation District in California's sizzling eastern desert. She said it was about 115 degrees when the power went out.