A major power outage, which left more than six million people in California and Arizona in darkness, was caused by a single maintenance worker, it has been revealed. The power cut took two nuclear reactors offline, grounded flights, caused major traffic jams and trapped people in elevators and on fairground rides in both states. San Diego bore the brunt of the blackout and most of the nation's eighth-largest city was darkened. The city trolley system that shuttles thousands of commuters every day was shut down and rush hour traffic hit gridlock. APS, Arizona's largest electricity provider, said a utility worker...