Interstate 15 traffic was heavily backed up due to a vegetation fire, sparked after a motor home caught fire Friday afternoon, authorities said.

Reports of a car fire on northbound I-15 just south of Bailey Road were received at 12:05 p.m. Friday. According to CHP logs, a motor home on the right shoulder had caught fire.

By 12:30 p.m. the flames had spread to two acres of brush on the right shoulder and one acre on the center divider of the freeway, the logs show.

Responding authorities requested a full closure of all northbound lanes of I-15 to combat the flames and stop the spread. The No. 1 southbound lane was also temporarily closed. The No. 2 and 3 northbound lanes of the freeway have since been reopened.

San Bernardino County Fire Department Captain Jeff Allen said several County Fire personnel, including a medic engine, two water tenders and a battalion chief, were on scene to assist Bureau of Land Management firefighters with the blaze.

County Fire Battalion Chief Dave Meddles, who was on scene, said the motor home was fully engulfed when the blaze began to spread to surrounding brush. As of 3:30 p.m. Friday, the blaze had burned through an estimated 50 acres, Meddles said, with firefighters able to stop any further rate of spread.

Two occupants in the motor home, along with their cat, were able to escape the blaze without injury. Other than treating a motorist who suffered a medical emergency while stuck in traffic, no other injuries were reported, Meddles said.

The incident caused heavy traffic delays in both directions, with Meddles mentioning northbound traffic was backed up to Halloran Springs. The No. 1 northbound lane of the freeway remained closed as of 3:00 p.m. Motorists are urged to use caution and expect delays.

The cause of the fire is currently unknown. Daily Press messages to the Barstow CHP office and Bureau of Land Management were not immediately returned.

This story is developing and more information will be updated as it is received.

Paola Baker may be reached at 760-955-5332 or PBaker@VVDailyPress.com. Follow her on Twitter at @DP_PaolaBaker.