The fire started in the Cajon Pass along Interstate 15 - the main highway between Southern California and Las Vegas - and quickly chewed through bone-dry brush. As flames closed in, drivers and passengers ran from their vehicles.
Fanned by hot desert winds, flames swept 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. Hundreds of other motorists turned onto side roads to get away from the flames.
A car-carrying tractor-trailer and a boat were among the losses left smoldering on the highway.
VIDEO: Flames engulf big rig on 15 Freeway as North Fire spreads
The fire reached Sage Street in the rural desert 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 are threatened. There were 22 engines, six air tankers, three helicopters, a bulldozer and hundreds of firefighters.
An evacuation center was set up at Serrano High School, 9292 Sheep Creek Road in Phelan. An animal shelter was opened at San Bernardino County Fairgrounds, 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 15 Freeway were reopened at about 8:30 p.m., but southbound lanes remained closed. Caltrans advised commuters to avoid the area because heavy delays were expected.
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.
(Some information from the Associated Press.)