LOS ANGELES -- A rare summer storm allowed firefighters to contain 60 per cent of a wildfire that swept across a California interstate highway, torching vehicles and sending people running for their lives.

Light rain and moist air dampened the blaze in the mountainous Cajon Pass, 89 kilometres northeast of Los Angeles, the main artery between Southern California and Las Vegas.

The wind-driven fire was sparked Friday afternoon below the elevated lanes of Interstate 15. Pushed by 40 mph (64 kph) winds, it raced up a hill and onto the traffic-clogged freeway, trapping hundreds of people amid a cauldron of smoke, flames and ash.

The flames destroyed 20 vehicles on the freeway before heading into the neighbouring community of Baldy Mesa, where it burned seven homes and destroyed 44 more vehicles.

In all, the fire burned about 22 square kilometres.

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

California is in the midst of severe drought, and wildfires are common. Some break out near freeways, but it's very unusual to have vehicles caught in the flames.

It being a Friday afternoon, however, Interstate 15 was typically jammed with vehicles travelling between Los Angeles and Las Vegas. Adding to the congestion was construction work in the area.

Another wildfire that broke out Friday night in the San Gabriel Mountains and forced the evacuation of 300 campers in nearby Wrightwood is 35 per cent contained after burning about 200 acres.