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HESPERIA, Calif. — A wildfire swept across a Southern California freeway Friday afternoon, causing several vehicles to burst into flames.

It was not immediately clear if anyone was hurt in the blaze that broke out Friday afternoon along Interstate 15 in the Cajon Pass, the main route between Southern California and Las Vegas.

Multiple ambulances have been called to the scene.

U.S. Forest Service spokesman John Miller told CBS Los Angeles the the fire in the Cajon Pass has burned at least 2,000 acres and is moving fast.

Firefighting aircraft were temporarily grounded by drone activity in the skies overhead but water drops have since resumed, reports CBS News correspondent Danielle Nottingham.

The fire led authorities to shut several freeway lanes, causing traffic to back up for miles.

Fire officials initially ordered drivers to stay in their cars but many abandoned their vehicles and tried to walk to safety.

There are mandatory evacuations for the surrounding neighborhoods in San Bernardino County.