CAJON PASS (KABC) --A fast-moving brush fire swept across the 15 Freeway between State Route 138 and Oak Hill Road in the Cajon Pass Friday afternoon, destroying 20 vehicles, burning at least four structures and prompting mandatory evacuations.
The fire broke out near the northbound lanes of the 15 Freeway at about 2:30 p.m. As of 8:50 p.m., the fire had charred 3,500 acres and was five percent contained, according to the U.S. Forest Service.
Fanned by hot desert winds, the fire spread across the 15 Freeway and burned several vehicles that were trapped in standstill traffic. Twenty vehicles were destroyed and 10 others were damaged, San Bernardino County Fire officials said.
VIDEO: North Fire sweeps across 15 Freeway, burns cars
California Highway Patrol spokesman Steve Carapia said 50 to 75 vehicles were left abandoned on the freeway, making it difficult for emergency responders. A car-carrying tractor-trailer and a boat were among the losses left smoldering on the highway.
Hundreds of other motorists turned onto side roads to get away from the flames.
VIDEO: Flames engulf big rig on 15 Freeway as North Fire spreads
The fire reached Sage Street in the rural community of Baldy Mesa, prompting mandatory evacuations east of Sheep Creek Road, north of State Route 138, west of the 15 Freeway and Highway 395, and south of Phelan Road.
Four structures were destroyed and at least 300 homes were threatened in the area. There were 22 engines, six air tankers, three helicopters, a bulldozer and 1,000 firefighters battling the North Fire.
An evacuation center has been set up at Serrano High School at 9292 Sheep Creek Road in Phelan. An animal shelter was opened at San Bernardino County Fairgrounds at 14800 7th Street in Victorville.
Full list of North Fire road closures and evacuations
Five drones temporarily halted air tankers that were fighting the North Fire. Officials grounded the firefighting planes for 15 minutes out of fear that the drone would collide with the aircrafts.
PHOTOS: North Fire erupts next to 15 Freeway in Cajon Pass
Two lanes on the northbound and two lanes on the southbound 15 Freeway were reopened at about 8:30 p.m. All northbound lanes, except one, were expected to be reopen Saturday. Caltrans advised commuters to avoid the area because heavy delays were expected.
The road on the 15 Freeway where two semi-trucks and a boat trailer burned damaged the top level of concrete. Caltrans crews were working on repairing the damage overnight into Saturday. About 3,000 feet of guard rail was also destroyed.
The cause of the fire remains under investigation, but firefighters first responded to a report of a vehicle on fire on the northbound 15 Freeway between State Route 138 and Oak Hill Road.
The 15 Freeway is the main route between Southern California and Las Vegas.