SAN DIEGO, Sept. 9 (UPI) -- The U.S. government said Friday it is launching an investigation into a massive blackout that covered a wide swath of Southern California.
The Federal Energy Regulatory Commission said in a written statement it would carry out the probe in conjunction with the North American Electric Reliability Corp.
"This inquiry is an effective way for us to protect consumers and ensure the reliability of the bulk power system," FERC Chairman Jon Wellinghoff said.
The investigation will look into the origins of the outage, which occurred at mid-afternoon Thursday when an Arizona Public Service worker replacing some equipment near Yuma somehow knocked a high-voltage transmission line feeding power to San Diego Gas & Electric Co. offline. The resulting interruption caused the big San Onofre Nuclear Generating Station and other conventional power plants in San Diego County to shut down.
"We have never had this happen before and we see no reason it will happen again," SDG&E Vice President Dave Geier said at a news conference Thursday night.
An estimated 1.4 million people in Southern California and an equal number in Baja California, Mexico, had to spend most of the night in candlelight without air conditioning or other modern conveniences. Stores and restaurants were closed and darkened streetlights created rush-hour traffic jams and scores of fender-benders.
Electricity was restored to most areas by dawn Friday; however, schools were closed across much of San Diego County.
The San Diego Union-Tribune said 1.9 million gallons of untreated sewage spilled into the Pacific from treatment plants that had been knocked offline, forcing officials to close several beaches into the weekend.
