In what power officials called an "unprecedented event," massive outages swept all of San Diego County on Thursday, and hit Coachella Valley, southern Orange County, and parts of Mexico. On a hot day, the outage shuttered businesses, closed schools and snarled traffic. An employee at a power substation in southwest Arizona likely caused the outage. Arizona power officials said the employee was carrying out a procedure at a substation in North Gila northeast of Yuma. They didn't immediately explain the procedure. Authorities say the outage should have been limited to the Yuma area. They were investigating why it wasn't contained. All 1.4 million customers of San Diego Power and Electric were without power at mid-afternoon Thursday. In all, in Arizona, California and Mexico, more than 5 million were without power. In a news conference the utility covered on its Twitter feed, it said that "Both major connections to our region have been lost .... This could go into tomorrow in some areas." By around 8 p.m., service began to be restored to Orange County. And officials said it would still be until the end of the day tomorrow before most power was restored. In anticipation, San Diego Unified Public School canceled school for Friday. According to the Arizona Daily Star, Mike Niggli, chief operating officer of SGD&E, said "To my knowledge this is the first time we've lost an entire system."



Traffic gridlock in San Diego at 5:51 p.m.

The outage triggered a shutdown of San Onofre's two nuclear reactors. John Wayne Airport was not affected by the power outage, but the San Diego International Airport's air traffic control tower no longer had power and operations there were halted except for inbound flights, which stopped at 6:30 p.m. Amtrak spokesman Marc Magliari says two Pacific Surfliner trains couldn't continue southward past Los Angeles after power was lost Thursday afternoon. Passengers who intended to travel to San Diego were stopped at Los Angeles' Union Station. Service on one Surfliner train traveling north to Los Angeles from San Diego was also canceled. CBS8 was reporting that the San Diego Zoo and Balboa Park museums were shuttered because of the outage. San Diego's trolley service was suspended. Outages in the Coachella Valley were being reported, including the transmitter site for KPCV. Many police stations were using generators for power.

SoCal Edison reported that 4,208 of their customers were without power. The Orange County communities that are affected include Laguna Niguel, Dana Point, San Juan Capistrano, and San Clemente, along with unincorporated areas north of San Clemente and east of San Juan Capistrano. But there’s a silver lining to the blackout in the Southland. Stargazers are excited that the skies will be dark for a change. “As long as the power stays out and the lights don’t come back on this evening, you’ll actually be able to in downtown San Diego and look up and actually see a large number of stars," said Bill Carlson of the San Diego Astronomy Association. "We have beautiful skies down here. A lot of the big observatories are here — Palomar, Mount Laguna, but because of all the light pollution you just can’t see ‘em most of the time. But tonight with all those lights turned off, you’ll be able to see a gorgeous sky.”