LOS ANGELES — Authorities were trying to help hundreds of motorists stranded in the snow Thursday after a powerful storm forced the closure of California's major north-south interstate in the mountains north of Los Angeles.

Traffic was halted in both directions on Interstate 5 in Tejon Pass, which rises to an elevation of 4,144 feet between the Los Angeles Basin and the San Joaquin Valley.

Early Thursday, a commercial inspector for the California Highway Patrol said officers and transit workers still were escorting down from the Pass area ''hundreds'' of motorists stranded by the snow and roadway closure. Officials were following drivers down the incline at very slow speeds.

It wasn't known how long the freeway would stay closed. The National Weather Service predicted two to four more inches of snow there Thursday.

''There are abandoned cars everywhere,'' said Wendy Gardner, a manager at Madd Bailey's Pub in Pine Mountain Club, where up to 10 inches of snow fell. ''We got hit around 2:30 in the morning and it hasn't stopped.''

A cold, upper-level low-pressure system off the Central Coast was responsible for the rain and snowfall, meteorologists said. Early Thursday, the storm had begun moving out of the region, the National Weather Service said.

Nearly a foot of snow was reported at the ranch community of Lockwood Valley in Los Padres National Forest, northwest of Los Angeles, the NWS said.

In Long Beach, heavy rain seeped through a plastic cover on the roof of an apartment building that was undergoing repair, damaging four apartments underneath, said Fire Department spokesman Will Nash.

''The plastic material couldn't hold up the heavy rain,'' Nash said.

A record 4.14 inches of rain were recorded at the Santa Barbara airport, topping the date's old mark of 2.45 inches set in 1943. More than 2¼ inches fell at the San Luis Obispo airport.