Southland Is Buffeted by Winds Gusting Up to 60 M.P.H. : Weather: Santa Anas knock down power poles, fan two fires and wreak havoc with commuters.

Gusty Santa Ana winds whipped through Southern California on Wednesday, knocking down power lines, creating airborne traffic hazards and sparking at least two fires.

As winds reached 60 m.p.h. early in the morning, 13 power poles snapped in the northeast San Fernando Valley, according to the Los Angeles Department of Water and Power. About 4,000 customers in Sylmar and Pacoima were left without electricity.

While homeowners dealt with loosened roof shingles and tiles and rattling windows, commuters from the San Fernando Valley to Riverside dodged flying palm fronds, fallen tree limbs and tumbleweeds that bounced in the air like jugglers’ balls.

In Malibu, the Los Angeles County Fire Department reported that a five-acre blaze started when a car crashed into a telephone pole in Malibu Canyon and sparked nearby brush. And in the Saddleback Mountain area of Orange County, a wind-fanned brush fire briefly caused anxiety but was contained after scorching just four acres, officials said.

A utility pole downed by wind near Pacific Coast Highway in Malibu left 145 customers, including parts of Pepperdine University, without power for two hours, a spokesman for Southern California Edison Co. said. In Orange County, more than 7,000 customers had service interrupted, mainly in Costa Mesa and Santa Ana. Several people were stranded in a Costa Mesa City Hall elevator for about an hour, officials said.

Wind blew down fencing along the center divider in several sections of Interstate 15 in Riverside County, the California Highway Patrol reported, but traffic was not impeded. Waves of wind-borne dust and debris slowed motorists to 5 m.p.h. in some sections of Interstate 10 between Ontario and San Bernardino.

“We’re advising extreme caution,” CHP spokesman Mark Mezzano said.

The CHP issued travel warnings for campers and trailers throughout the Inland Empire and on all freeways north of California 118 to the Grapevine, including the Antelope Valley.

The wind played a practical joke on some Orange County motorists Wednesday morning, causing them to believe that part of the Santa Ana Freeway was closed, the CHP said. The wind blew off a canvas flap on a sign about an upcoming temporary closure near the El Toro “Y” interchange. Motorists seeing the sign made a detour onto the San Diego Freeway, intensifying the usual bottlenecks on that freeway.

On Norris Street in Pacoima, two unoccupied cars became stuck under an old tree that was uprooted by the wind and fell across them, breaking their windows and flattening their tires.

Carmen Rojas, whose two sons own the vehicles, heard “a loud popping noise” about 4 a.m. “I thought a bomb had gone off,” she said.

In Pasadena, a worker at the Rose City Diner lost a Christmas decoration, a nine-foot papier-mache Nutcracker-style soldier, that he was removing from the building.

“The wind just took it down the street” like tissue paper, owner Sal Casola said.

Winds of 20- to 40-m.p.h. were expected to continue today, with gusts “pretty common around 50 m.p.h.,” said Marty McKewon, meteorologist with WeatherData Inc., which provides forecasts for The Times. “But . . . I think we’ll see a decrease in the afternoon.”

The National Weather Service said the winds were being caused by a high-pressure center stalled over Idaho and Nevada.

Santa Ana winds tend to be most intense along mountain ridges and through passes, McKewon said.

“There can be great differences across the area,” he added. “At times today the Civic Center had only up to 10-m.p.h. wind gusts while Santa Ana had 50 m.p.h.”

Wednesday’s Civic Center high reached 74 degrees. Today will be slightly warmer, with highs in the mid to upper 70s, forecasters said.

Times staff writers Julio Moran in Los Angeles, Joanna Miller in Ventura County, Jenifer Warren in Riverside County and Bill Billiter in Orange County contributed to this story.