A mudslide triggered by a sudden cloudburst caused a hillside near Griffith Park to collapse, trapping as many as a dozen cars in mud.

No one in the cars was injured and nobody had to be escorted from their vehicles, said Brian Humphrey, a spokesman for the Los Angeles Fire Department.

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The slide struck shortly before 1 p.m. along a 100-yard stretch of Forest Lawn Drive, near the entrance to Forest Lawn Cemetery. It covered the roadway in mud 2 or more feet deep and brought large boulders and tree limbs cascading down from the hillside. The road was closed until utility crews could shovel up the debris.

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Mud also seeped into the hallways at a pair of apartment buildings on the street.

Firefighters said several motorists were safe, but stranded by mud near the Warner Bros. Burbank studio's employee parking garage on the south side of the Los Angeles River. Skiploaders form the city's parks department dug a path, and marooned drivers began being escorted out of the garage at 3 p.m.

The slide was the worst of several that struck Los Angeles hillsides during a driving rainstorm that arrived late Friday night. None of them caused any immediate danger to homes or people.

Humphrey said the Griffith Park-area slide was typical for the first big rainstorm of the season.

Sprawling Griffith Park was the site of a wildfire last spring that burned across more than 800 acres, denuding hillsides and destroying hiking trails. But Humphrey said the slide that struck just outside the park didn't occur in the burned area.

Last May, a fast-burning fire consumed 817 acres of steep parkland. City officials are seeking a $50 million reforestation project, but had warned that denuded slopes could trigger mudflows in rain storms.

Saturday's slide came in the midst of a late-summer storm that prompted the National Weather Service to issue flood watches for Los Angeles County, San Diego County and other parts of Southern California.

Rainfall totals by midday ranged from 1.5 inches at Mount Wilson, north of downtown, to about an inch in parts of the city's San Fernando Valley.

One of the worst instances of flooding in the region occurred in Costa Mesa, where a woman had to be rescued from the roof of her van after it became trapped in water.

The storm also brought scattered power outages to the region.

The Associated Press contributed to this report.