Power is being restored in Arizona today and steadily returning to parts of Southern California and Mexico after a black out left millions in the dark last night.
The outage was accidentally triggered 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. said.
The black out left southwestern residents sweltering without air conditioners and paralyzed some San Diego freeways and airport traffic.
It was unclear why that mishap, which normally would have been isolated locally, triggered such a widespread outage. The company said that would be the focus of a probe.
The San Diego area was hit especially hard with power severed to all of San Diego Gas & Electric Co.'s 1.4 million household and business customers, the company said.
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Residents poured into the few bars that remained open in downtown San Diego after dark, some donning reading lights on their heads like miners. A pair of men carried flaming tiki torches -- usually planted in backyards -- to see their way down the pitch black street.
"It's surreal," said Myrna Contreras, 35, sitting in the patio of a candlelit bar. "It's upbeat. It's friendly."
The outage extended into southern Orange County, across California's inland deserts, as far east as Yuma, Ariz., and into Mexico, where officials said power was out in northern Baja California's two biggest cities, home to roughly 2.5 million people.
The region is home to some 6 million people, though it was impossible to say exactly how many had lost power.
By early Friday, energy had been restored to more than some 930,000 users in the region, according to combined tallies provided by officials in Arizona, California and Mexico.
Yuma and its surroundings in Arizona's southwestern corner was fully back after seeing power knocked out for 56,000 customers.
"We have a ways to go but were starting to see a bit of progress right now," said Mike Niggli, chief operating officer of San Diego Gas & Electric Co.
Niggli said he expected a "very steady advance" in restoring power from early in the day through the middle of the afternoon. He urged people to turn off their air conditioners and wait a bit once the electricity comes back on to avoid a surge and another outage.
Two reactors at a nuclear power plant along the coast went offline after losing electricity, but officials said there was no danger to the public or workers.
Authorities quickly ruled out an intentional act or, in the anxious days leading up to the anniversary of Sept. 11 attacks, any suggestion of terrorism.
"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.
It's possible that extreme heat in the region also may have caused some problems with the transmission lines, Niggli said.
During the night, much of San Diego was in darkness, and all outgoing flights grounded at its main airport, Lindbergh Field.
There were no immediate reports of major injuries connected with the outage. Officials in San Diego and elsewhere said they were on alert but no major problems had arisen, including any signs of looting or other unrest.
Gas stations were shuttered and most shops and restaurants shut down.
There were reports of minor traffic accidents as the outage caused mayhem on the streets without stoplights during rush hour.
Leah Walden, 59, said she saw about five fender benders on her drive from her accounting job in suburban Spring Valley to a wedding-cake tasting in San Diego.
"People are irritated. They don't want to wait," said Walden, adding that about 15 cars went into reverse on a freeway veering out of the way of oncoming traffic to escape traffic jams. "That's how nuts people are."
In the beach town of Encinitas north of San Diego, Tim Grenda, 41, put a positive spin on it, pointing out that his hot yoga class was cooler because of the outage.
The class, usually performed at 104 degrees, was closer to 99 degrees because a furnace used to pump in heat had been knocked out.
"It was hot enough for me, but it wasn't quite as intense as the usual practice," he said.
Rosa Maria Gonzales, a spokeswoman with the Imperial Irrigation District in California's sizzling eastern desert, was less enthusiastic -- temperatures were well into triple-digit territory when the power went out.
"It feels like you're in an oven and you can't escape," she said.
Jason Shafer, 29, said it was hot and uncomfortable in Palm Desert, and he didn't think things were going to get much better as the night went on.
"It's hard to sleep in anything above 80 degrees inside the house," he said. "I'm hoping they're going to get it fixed by bedtime."
Shafer said he and his wife would try to find a friend's house they can stay for the night, and if not, they might end up sleeping on the tile floor.
"We'll strip down to our skivvies and make the best of it," he said.
The blackout extended south of the border to Tijuana, Mexicali and other cities in Mexico's Baja California state, which are connected to the U.S. power grid, Niggli said. Police on both sides sent in re-enforcements to prevent looting and other crime in their cities, but none was reported.
In Tijuana, people wandered out of their hot homes into the street to cool off while restaurants scrambled for ice to save perishable food.
A backup system allowed officials to continue operating crossings from Arizona to California, said Customs and Border Protection spokeswoman Jackie Wasiluk.
Niggli said that the all 1.4 million of the San Diego utility's business and household customers were affected.
When asked how many people that represented, he pointed out the population of San Diego County is roughly 3 million and the power was knocked out for most of the county.
He also said that in areas of Orange County and in outlying desert areas, several hundred thousand people were affected.
Aside from clogged freeways, San Diego commuters also had to deal with the shutdown of the trolley system that shuttles thousands of commuters every day.
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 came more than eight years after a more severe black out in 2003 darkened a large swath of the Northeast and Midwest. More than 50 million people were affected in that outage.
In 2001, California's failed experiment with energy deregulation was widely blamed for six days of rolling blackouts that cut power to more than 3 million customers and shut down refrigerators, ATMs and traffic signals.
Based on reporting by The Associated Press.