Traffic on Interstate 5 slowed to a crawl Sunday afternoon as Kern County firefighters worked to contain two wildfires on the Grapevine near the Fort Tejon exit, a Fire Department spokesman said.

"Traffic is moving at maybe 10 miles per hour," Kern County Fire Department spokesman Corey Wilford said late Sunday afternoon as even he was caught in the traffic jam that extended as far down the mountain as the junction of Highway 99 and I-5.

Some 50 homes were evacuated, and Frazier Mountain High School was opened to accommodate those who needed a place to stay, he said. But ultimately, the school wasn't be needed as firefighters began to get a handle on the pair of 3-acre fires on the southwest side of Lebec Road.

According to a later news update, the department placed fire engines and patrols around structures in O'Neil Canyon while U.S. Forest Service engines attacked the active fire with hose lines.

With assistance from the Kern County Sheriff's Office and the California Highway Patrol, residents were told to evacuate to Frazier Mountain High School. However, by about 8:30 p.m. all residents were able to return safely to their homes.

Firefighters were expected to be on-scene throughout the Sunday night and into Monday morning to complete mop-up of the fire area, fire officials said.

The cause of the fire was determined to be a faulty catalytic converter from a passing vehicle.