The blaze was reported shortly after 2 p.m. on the northbound 71, near the 91 Freeway and south of Euclid Avenue in Chino, according to the California Highway Patrol.
The Euclid Fire went from about 75 acres to an estimated 120 acres within an hour. The acreage was mapped throughout the day, and fire officials determined as of 10:30 p.m., the blaze was at 120 acres with 15 percent containment.
No evacuation orders were in place, and no structures were threatened. Fire officials said the blaze was in a rural area near the Prado Dam.
The CHP said a white sedan caught fire, possibly from overheating, and the vehicle was quickly engulfed. Flames jumped from the car to dry vegetation nearby, culminating in a brusher that prompted the CHP to shut down all northbound lanes going into San Bernardino County. Lanes were later reopened.
Firefighters from Cal Fire, Chino and Corona fire departments were working to get a handle on the blaze.
Cal Fire officials said one firefighter was being evaluated for injuries that were not life-threatening.
City News Service contributed to this report.