A wildfire that swept across a busy California freeway, sending people running for their lives, was calmed by rain on Saturday.

Some firefighting crews were then free to be shifted to another blaze that forced hundreds of campers to evacuate, including a Girl Scout troop.

At least five campgrounds near the fire were emptied, sending 300 campers, including 130 children with special needs, to a nearby high school, the Los Angeles Fire Department tweeted.

The rain and lower temperatures helped pacify the fire that had burned over Interstate 15 on Friday in Cajon Pass, a mountainous area 88.5 km northeast of Los Angeles.

The fire destroyed 20 vehicles on the freeway linking Southern California and Las Vegas before burning three homes and 44 more vehicles in the community of Baldy Mesa.

The fire was 5 percent contained after charring 14.24 square km. Highway officials reopened most of Interstate 15. Firefighters turned their attention to protecting 700 homes in the Baldy Mesa area.

About 2,800 people remained evacuated and nearly three dozen spent the night at a temporary shelter. US Forest Service spokeswoman Carol Underhill said rain was helping firefighters and the fire wasn't growing.

The fire had sparked sheer chaos when it began next to Interstate 15.

Fueled by 64-km/h winds, the blaze raced uphill and onto the traffic-clogged freeway, temporarily trapping hundreds of people amid a caldron of smoke, flames and ash.

Amazingly, only two people were injured. Both suffered minor smoke inhalation, authorities said, but declined medical attention.

Among those trapped by the flames was Lance Andrade, a 29-year-old railroad conductor who found himself caught in the traffic jam just as the fire jumped the freeway.

Flames surrounded him and the others. A panicked-looking firefighter ordered everyone to take cover, and Andrade said he huddled with four other men and two elderly women in a tractor-trailer until the flames passed.

One of the women, who had become separated from her family, began to cry. Everybody was terrified.

"You could hear the explosions from people's vehicle tires popping from the heat," Andrade said.

AP - Reuters