UPDATE: Power Restored To Much Of The Region

9/9 7:30 a.m. UPDATE: Most of the nearly six million people in California, Arizona and Mexico have power again a day following an historic blackout.

Officials are warning, however, that the electrical grid is still quite fragile. Residents and businesses throughout the Southland are being asked to go easy on power usage to help reduce the strain.

Electricity came back in San Diego early Friday. Customers in Riverside and Orange counties were back on line late Thursday night.to read more about the blackout in Riverside County.

Mexico's electrical utility said the lights are on for 1.1 million customers, or 97 percent of those who lost power. By Thursday night, power was also restored to all 56,000 customers in Yuma, Ariz.

San Diego was hit especially hard by the blackout, which began just after 3:30 p.m. Thursday and impacted all of San Diego Gas & Electric Co.'s 1.4 million household and business customers. It left residents sweltering in stifling temperatures and it halted some freeway and airport traffic.

The outage extended into southern Orange County, across California's inland deserts, as far east as Yuma and into Mexico. The region is home to 6 million people, though it was impossible to say exactly how many lost power. Mike Niggli, president and COO of San Diego Gas & Electric Co., estimated the number was well into the millions. ( to watch news conferences on the outage featuring Niggli.)

The failure occurred after 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.

It was unclear why that mishap, which normally would have been isolated, sparked such a widespread outage. The company said that would be the focus of an investigation.

"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 also may have caused some problems with the transmission lines, Niggli said.

City schools, state universities and community colleges are closed today in San Diego County. Some beaches there are also closed because the outage caused a 3.2-million sewage spill. During the night, much of San Diego was in darkness, and all outgoing flights grounded at its main airport, Lindbergh Field. The airfield was open and had power Friday morning but authorities said some airlines may have cancelled flights.

There were no immediate reports of major injuries connected with the outage. Officials across the Southland have been on alert but no major problems were reported. Major looting and civil unrest were not reported.

There were reports of minor traffic accidents as the outage caused mayhem on the streets without stoplights during rush hour.

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.

Two reactors at the San Onofre Nuclear Power Station went offline after losing electricity, but officials said there was no danger to the public or workers. --Toni McAllister and the Associated Press contributed to this report.

9/9 UPDATE 12:30 a.m.: A massive power outage left nearly 6 million people in the Southern California, Arizona and Mexico without electricity Thursday, but slowly the lights are coming back on.

San Diego was hit hardest by the blackout that started around 3:30 p.m. (see attached map to view impacted areas).

The blackout extended east to Yuma, Ariz. where more than 56,000 people were temporarily without electricity; power was restored there about five hours later.

Power was restored to roughly 193,000 customers by 11 p.m. Thursday in about a dozen cities in San Diego and Orange counties, officials said. Nine of San Diego Gas & Electric Co.'s 115 substations were also back in service.

to read about the power outage in Riverside County.

"We have a ways to go but were starting to see a bit of progress right now," said Mike Niggli, president of SDG&E.

Niggli said he expected a "very stead advance" around 2 a.m. through the middle of Friday afternoon, but it could take up to two days to fully restore the power in some areas, Niggli said to watch the news conferences with Niggli.

Officials said the massive blackout was likely caused by an employee removing a piece of monitoring equipment at a power substation in southwest Arizona. When a transmitter line between Arizona and California was disrupted, it cut the flow of imported power into the most southern portion of California, the power officials said. The extreme heat in some areas also may have caused some problems with the lines, Niggli said.

The power loss should have been limited to the Yuma and the power company was investigating why it spread to such a large area, including Mexico. Officials ruled out terrorism.

"Essentially we have two connections from the rest of the world: One  from the north and one is to the east. Both connections are severed," Niggli said.

The blackout caused gridlock in San Diego. All outgoing flights from San Diego's Lindbergh Field were grounded and police stations were forced to use generators to accept emergency calls across the area.

San Diego officials also announced schools would be closed Friday as a precaution. Public transportation in San Diego is also expected to be limited on Friday.

Two nuclear reactors at the San Onofre Nuclear Generating Station near San Clemente went offline after losing electricity, but officials say there was never any danger to the public or workers. San Onofre is Southern California’s largest source of electricity. Jointly owned by Southern California Edison, SDG&E, and the city of Riverside, the units can generate 2,200 megawatts of power.--Toni McAllister

9/8 UPDATE at 9:30 p.m.: During an 8 p.m. news conference hosted by San Diego County Board of Supervisors Chairman Bill Horn, officials said that power is slowly coming back online in Southern California but it could take up to three days for some areas to be fully restored. (to view the 8 p.m. and a 10 p.m. news conference.)

Customers in Tijuana and Mexicali up through San Diego, Orange and Riverside counties have been affected by the blackout that began shortly after 3:30 p.m. Thursday.

In total, nearly 1.4 million ratepayers have been impacted, equating to millions and millions of people across the Southland without power, said SDG&E President Mike Niggli during the news conference.

Power restoration efforts will take place in phases, Niggli said.

There was no word yet on which areas would come back first, but some customers in Orange County and parts of North County San Diego are back up, SDG&E officials are reporting.

Riverside County is not expected to be back online until early Friday morning. for more on Riverside County's outage.

The massive Southern California outage is believed to have been triggered by an employee removing a piece of monitoring equipment that was causing problems at a power substation in southwest Arizona, near Yuma, Niggli said. The power company, Arizona Public Service, is investigating why the outage wasn't contained to the Yuma area.

Niggli and Arizona Public Service offiicials say it will take some time before all questions are answered about what caused the widespread outage.

SDG&E officials acknowledge that extreme temperatures across the Southwest have increased power demand and that likely contributed to the failure. --Toni McAllister

9/8 UPDATE at 5:50 p.m.: A massive power outage hit three counties around 3:35 p.m. Thursday on one of the hottest days of the year, affecting people from south Orange County to Arizona and Tijuana. It halted phone service and knocked some radio stations off the air.

Some 1.4 million customers were without electricity, according to a spokesman for San Diego Gas & Electric Co.

San Diego, Orange and Riverside counties are affected.

( for an update on Riverside County's outage.)

A spokeswoman for the San Diego Office of Emergency Services told KOGO radio that it was in a "level 3" emergency.

An SDG&E spokesman said the outage could last into Friday after a "large switching station" in Arizona was knocked out.

A "cascading event" overwhelmed the system, leading to "too many outages in too many places," he said at SDG&E headquarters. The San Onofre nuclear generating station was down.

The Escondido and Otay Mesa power plants were to be brought online first, "working from the inside out," the utility said.

"This was a fairly severe event," SDG&E said at its Kearny Mesa base. This could be an extended outage, the spokesman said. 

"Just chill out while the power is out," he said. He urged people to turn their air conditioning and other major appliances off in anticipation of the power being restored.

SDG&E said it would post updates on Twitter at twitter.com/sdge

"We don't know what happened to the [Arizona] line; all we know is that the line is out. We don't know exactly why it went out. We have no indication that there is an act of terrorism at this time."

A ham radio operator told KOGO radio at 4:40 p.m. that the Coachella and Salton Sea power plants have gone down. No confirmation yet from officials.

The San Diego Office of Emergency Services told KOGO radio that residents shouldn't use landline phones or cell phones.

Traffic accidents were reported in the Mission Valley area, and major backups were reported on local freeways as offices emptied early.

Many radio stations are out, but KOGO said it was running on a generator. Los Angeles is not affected. All three trolley lines are reported halted. Lindbergh Field halted departures but not arrivals. San Diego State University shut down.

The following was tweeted by @SDG&E:

"We understand power is out, we are working on the cause and solution. We do not have a restoration time yet."

Phones were jammed throughout the county, and KOGO was told that Ensenada and other Baja California cities lost power.

The California Highway Patrol reminded drivers to treat intersections with a flashing red light as stop signs. About 50 accident calls were pending "the last time I checked," a CHP spokesman told KOGO.

More on Patch as events unfold.

Adam Townsend contributed to this report.

9/8 ORIGINAL POST: A massive power outage felt from south Orange County to Arizona and even Tijuana hit around 3:35 p.m. Thursday, affecting landline phone service as well as radio transmissions.

A ham radio operator told KOGO radio at 4:40 p.m. that the Coachella and Salton Sea power plants have gone down. No confirmation yet from officials.

San Diego Gas & Electric Co. was not answering phone calls, but it tweeted that staff is working on finding the source of the problem.

The San Diego Office of Emergency Services told KOGO radio that residents shouldn't use landline phones or cell phones.

Traffic accidents were reported in the Mission Valley area, and major backups were reported on local freeways as offices emptied early.

Many radio stations are out, but KOGO said it was running on a generator. Los Angeles is not affected. All three trolley lines are reported halted. Lindbergh Field halted departures but not arrivals.

The following was tweeted by @SDG&E:

"We understand power is out, we are working on the cause and solution. We do not have a restoration time yet."

More on Patch as events unfold. --Adam Townsend contributed to this report.