(CNN) – Water-dropping helicopters and hundreds of firefighters are battling a blaze in Los Angeles County that has forced the evacuations of thousands of at least 5,000 people, according to authorities.
The wildfire, which broke out Saturday afternoon, has burned about 500 acres in and around Calabasas — a relatively affluent area which is home to a handful of celebrities, including Jessica Simpson and Toni Braxton, authorities said.
“This fire has a long way to go before firefighters can actually contain [it],” CNN Meteorologist Derek Van Dam said.
More wind will help bring up humidity from the coast, Van Dam said, which will help firefighters.
About 5,000 residents have been evacuated so far, the majority of which faced mandatory evacuations, according Deputy Jeffrey A. Gordon with the Los Angeles Sheriff’s Department.
Evacuated residents are being urged to go to nearby Agoura High School.
Gordon said the fire was sparked at about 4:15 p.m. PT, when a pickup truck struck a power pole on Mulholland Highway in Calabasas.
“Witnesses reported that the truck was traveling at a high rate of speed before colliding into a power pole, causing the pole to fall and a transformer to explode, thus igniting the Calabasas fire,” he said.
Temperatures in nearby Topanga reached the mid-90s earlier in the day, according to the National Weather Service.
The fire, which has been dubbed the “Old Fire” due to its proximity to Old Topanga Canyon Road, was 15% contained as of late Saturday local time, according to the LA County Fire Department.
More than 300 firefighters were battling the blaze, according to Los Angeles Fire Captain Roland Sprewell.