Overload of electrical circuit caused a power failure in Los Angeles, the second-largest U.S. city, darkened downtown and several nearby cities, trapping people in elevators, disrupting refineries and snarling traffic.
The blackout started around 12:35 p.m. local time, and almost all who lost power had it restored by 2 p.m., said Kim Hughes, a spokeswoman for the Los Angeles Department of Water and Power, the nation's largest municipal utility.
Power was lost in an area with about 2 million people after a worker with the utility accidentally overloaded a transmission line, tripping circuit protectors, Hughes said. Overloading the line caused an automatic shutdown of other lines to prevent damage to equipment.
"We wanted to put too many cars on the wrong freeway," Hughes said. "The system put the brakes on," reports Bloomberg.
According to Reuters, "The fact that this happened the day after Sept. 11 caused a heightened sense of concern," said Los Angeles Mayor Antonio Villaraigosa. "I am here to assure you that our city is prepared to handle these situations. In fact power was restored to the vast majority of DWP customers, 90 percent, within the first two hours."
Some, remembering the collapse of the World Trade Center towers on Sept. 11, abandoned their high-rise offices despite assurances from security personnel that they should remain at their desks.
"When they said to stay, I thought 'I'm going,'" clerical worker Erica Fernandez told Reuters.
State and local authorities have dismissed the videotaped threats, saying that there was no credible evidence of a plan for an imminent terrorist strike against Los Angeles.
Department of Homeland Security spokesman Russ Knocke said federal agents monitored the situation but said there was "no indication of a nexus to terrorism."