Update 8:04 p.m.
About 90 percent of the power has been restored in Imperial and Coachella valleys as of 7:30 p.m., an IID spokesperson said.
Pockets of areas may still be without power. Customers without power who notice that their neighbors have power are urged to call 1-800-303-7756 to report problems that may be related to issues beyond the outage.
Update 7:50 p.m.
The operating and protection protocols of the Arizona Public Service have become the focal point of an investigation into what caused a massive blackout earlier today that continues to affect a large swath of the border region between Southern California and Mexico, an official said.
Operating and protection protocols at the North Gila substation near Yuma typically would have isolated the resulting outage to the Yuma area, a press release from the Arizona utility stated.
The utility is currently working to restore power to the communities of Yuma, Somerton, San Luis and Gadsden.
Update 6:52 p.m.
An emergency cool center has been set up in El Centro for those who have yet to have powered restored.
The city's Community Center at 375 S. First St., has opened its doors and doesn't have a closing time as of yet, said Elizabeth Phillips, with the Imperial County chapter of the American Red Cross.
Traffic signals at Even Hewes Highway and Forrester Road, as well as Pitzer and McCabe roads are operational, said Maria Peinado, county emergency operation center spokesperson.
Update 6:19 p.m.
IID-owned power plants are currently providing electricity to area clients, although there is an unkown number of customers still without power, IID spokeperson Marion Champion said.
Both the county and IID have emergency command centers in place currently, Champion said.
Parts of El Centro, Brawley, Imperial and Niland are back up, while all of Westmorland and Holtville are back online, Champion said.
Update 6:09 p.m.
The Los Angeles Department of Water and Power and Southern California Edison have started setting up power feeds to the San Diego areas affected by a massive blackout that started over two hours ago, said Don Boland, executive director of the California Utilities Emergency Association.
Update 5:40 p.m.
The Imperial Irrigation District is reporting that power has been restored to most cities in the area, with Brawley expected to be back on line shortly.
San Diego Gas Electric officials announced the outage seems to have originated in Arizona and caused a transmission line from Arizona and from the north of SDG&E's region to both trip off.
An estimated 1.4 million people covered by SDG&E were reportedly without power as of 5 p.m.
Update 4:33 p.m.
According to police scanner traffic, power has been restored intermittently in parts of San Diego
and Yuma. Areas suchas Blythe in Riverside County reportedly never lost power.
Power has returned to parts of the Imperial Valley after a widespread power outage struck about 3:40 today. Widespread outages still remain in parts of Yuma, San Diego and Riverside counties.
News agencies from Baja California are also reporting outages in San Luis Rio Colorado, Mexicali and Tijuana.
IID General Manager Kevin Kelley said the district is still trying to determine what the cause of
the failure is.