A 100-acre brush fire sparked by a vehicle now is 20 percent contained but Interstate 17 near Cordes Junction remains closed in both directions.
It's caused a traffic backup for miles on one of the main routes to northern Arizona.
Black Canyon Fire Department officials say the Badger Fire was sparked about 2 p.m. Tuesday by an RV near the Sunset Point Rest Area and quickly grew due to wind gusts and dry conditions.
Television footage showed a frame of an RV still on fire with charred grass around it.
Crews are trying to stop the spread of flames along both sides of the interstate.
Arizona Department of Transportation officials say I-17 is closed in both directions near Sunset Point and there's no word on when the freeway will reopen.