Major power outage in California, Arizona, Mexico

LOS ANGELES—A massive power outage triggered traffic gridlock and left at least 1.4 million customers without electricity Thursday in sweltering southern California, Arizona and Mexico, officials said.

A number of people had to be rescued from stuck elevators and theme park rides including the world-famous SeaWorld in San Diego, reports said, while two units at a nuclear power plant tripped offline, as designed.

The failure on a 500-kilovolt line also left people without air conditioning or power for fridges at a time when the region has been sweating through a mini-heatwave.

San Diego Gas & Electric (SDGE) said an incident in the network between Arizona and California had caused the outage, which also affected neighboring Mexico and could continue into Friday.

“1.4 million of our customers are currently without power,” the company said on Twitter, adding: “An event happened between AZ and CA. Both major connections to our region have been lost.

“This outage has affected Mexico and Baja,” it said, referring to Baja California, the Mexican peninsula stretching south from below San Diego, below the US-Mexican border.

“This could go into tomorrow in some areas,” it warned.

Traffic lights were knocked out across the region, triggering monster traffic jams, while the Metrolink transport system in Orange County was disrupted.

Two units at the San Onofre power plant, one of California’s two nuclear plants, went offline automatically, officials said, adding that backup power was available.

Emergency services had responded to at least half a dozen calls to rescue people stuck in elevators, said Orange County Fire Authority spokesman Mark Stone.

Both SeaWorld and Legoland reported that visitors had to be rescued from rides, according to the San Diego Union-Tribune, although there was no immediate confirmation from either of the parks.

The California Independent System Operator Corporation (ISO) declared “a transmission emergency” after a 500 kilovolt (kV) high-voltage line from Arizona to California tripped out of service.

“The transmission outage cut the flow of imported power into the most southern portion of California resulting in widespread outages in the region,” it said in a statement.

APS, the Arizona power supplier, said 56,000 customers had been affected.

Temperatures have been sweltering in recent days in southern California, boosting use of air conditioning.

“Hot days in a row like we have had create lots of power flowing. Could have had an impact,” SDGE tweeted.