They left Peterson Air Force Base Tuesday afternoon. The planes are equipped firefighting systems, or MAFFFS.
The planes will fly low and slow to drop 25,000 pounds of fire retardant on the flames.
The reservists will be there as long as the job takes.
As of 4 p.m. Tuesday afternoon, a half million acres have burned from Los Angeles to San Diego.
Officials say at least 17 people have been killed. The fires have destroyed more than 1,500 homes.