A brush fire in San Bernardino prompted a partial closure of the northbound 15 Freeway Sunday afternoon.

The 15-acre Wagon Train Fire is burning vegetation “with a moderate rate of spread” and is being fought by U.S. Forest Service firefighters, the San Bernardino National Forest tweeted.

At 1:45 p.m., SBNF announced that forward progress had been stopped at 15 acres with the assistance of the San Bernardino County Fire Department, CalFire and the Rancho Cucamonga Fire Department.

The No. 4 and 5 lanes are closed for an “unknown duration,” CalTrans added.