The blackout that left millions of people in the dark overnight in San Diego, Orange County, and other parts of Southern California and Mexico, was apparently caused by one employee of the Arizona power company APS. The LA Times has the report from the power company:
"The outage appears to be related to a procedure an APS employee was carrying out in the North Gila substation, which is located northeast of Yuma," an APS press release said. "Operating and protection protocols typically would have isolated the resulting outage to the Yuma area. The reason that did not occur in this case will be the focal point of the investigation into the event, which already is underway."