Officials are working to restore electricity in southern California, parts of Arizona and northern Mexico after a major power failure cut the lights for more than five million people.
Authorities blame a transmission line in Arizona which automatically shut down two reactors at the San Onofre nuclear power plant near San Diego in California. They say an employee carried out a procedure at the planet, apparently causing the blackout.
Areas affected include much of San Diego, parts of Arizona, and the states of Baja California and Tijuana in northern Mexico. Officials say the power failure should last throughout Thursday night into Friday morning and possibly longer.
Power went out just before Thursday afternoon's rush hour, causing heavy traffic congestion and shutting down streetcar service. Radio and television stations were knocked off the air and flights at local airports grounded.