A power blackout hits Los Angeles

A blackout hit a large portion of the Los Angeles area Monday afternoon, snarling traffic at intersections and trapping people in elevators.

The blackout came a day after ABC aired a videotape of a purported al-Qaida member making terrorist threats against Los Angeles and Melbourne, Australia, on the fourth anniversary of the Sept. 11 attacks.

The city was investigating the cause of the outage. But Sgt. Catherine Plows, a police spokeswoman, said terrorism was not suspected.

The electricity was knocked out shortly before 1 p.m. after two power surges, and outages were reported from downtown to the coast and north into the San Fernando Valley, an area encompassing hundreds of thousands of residents and thousands of businesses.

Downtown high-rises went dark, fire officials said they received reports of people stuck in elevators, and stoplights went out at intersections across the city. Some neighboring cities also were affected.

The Police Department went on "full tactical alert," meaning no officers were allowed to leave work when their shifts were over.