Motorists were urged to avoid Interstate 15 in the Cajon Pass after a recreational vehicle fire spread to brush along the freeway and moved toward structures Tuesday afternoon, officials said.
Dubbed the Devore Fire, the flames broke out shortly after noon and had spread to 40 acres by 6 p.m. The blaze was 50% contained as of 9 p.m., according to San Bernardino National Forest officials.
The fire had earlier been spreading at a moderate rate and threatening structures in the Devore Heights, Hall Ranch and Mathews Ranch neighborhoods. But its forward progress was stopped by 5:30 p.m., firefighters said.
The No. 5 and 6 lanes of northbound Interstate 15 remained blocked north of Kenwood Avenue for cleanup and repair until further notice.
A bit further down I-15, at Duncan Canyon Road in Fontana, a big rig blaze unrelated to the Devore Fire caused a fire to spread about 1.5 acres before forward progress was halted. As of 8 p.m., southbound lanes No. 3 and 4 were reopened after cleanup.
Traffic was backed up on the interstate and motorists were urged to use caution and slow down, or if possible use an alternate route. If traveling south through Fontana, drivers were advised to use the 215 Freeway as a detour.
One firefighter suffered a minor injury while battling the Devore Fire, officials said. No further details on the circumstances were available.
The blazes broke out as a high-pressure weather system moves across Southern California, dialing up the heat. Temperatures were expected to hit 90 degrees in the Inland Empire and near 100 degrees in the Coachella Valley, according to the National Weather Service.
Earlier Tuesday, San Bernardino County fire officials had begun a prescribed burn operation south of Hesperia near Lake Silverwood. But the plans were scrapped for the rest of the day after the Devore Fire broke out.
Smoke from both the controlled burn and Devore Fire was expected to impact Oak Hills and eastern Hesperia, firefighters said.
