Worker 'Moving Equipment' Plunged 6M Into Darkness But probers wonder how simple screw-up spread so far, so fast By Mary Papenfuss, Newser User Posted Sep 9, 2011 1:32 AM CDT Updated Sep 9, 2011 6:07 AM CDT 18 comments Comments Workers in a bar make do without electricity last night in San Clemente, Calif. (AP Photo/Alex Gallardo) (Newser) – Power company officials believe a worker moving a piece of monitoring equipment in an Arizona utility substation likely turned off the lights yesterday for a massive 6 million customers stretching through southern California and Mexico. "This was not a deliberate act. The employee was just switching out a piece of equipment that was problematic," said a spokesman for Arizona Public Service. Searing San Diego took the brunt of the shutdown: All flights from the city's airports were canceled and police stations switched to generators so they could answer emergency calls. Two nuclear generators went offline after power shut down and the US-Mexico border was plunged into darkness. Power was restored last night for about a dozen cities in San Diego and Orange counties in California, reports AP. But most people affected spent the night without power. "It feels like you're in an oven and you can't escape," said an official working in California's baking eastern desert. Officials are investigating why a problem in Arizona spread to such a large area. They have ruled out terrorism.