The Boise Fire Department says that the Ourada Ranch Fire burned an area near Cartwright Road and Ourada Ranch Road and has grown to about 419 acres.
Firefighters had structure protections in place and say there was no immediate danger to homes in the area.
Officials say a local farmer helped make a fire break with a tractor pulling a large disc that helped fire crews.
The fire department requested additional aid from the Bureau of Land Management.
BLM responded with two engines, one water tender, one bulldozer, and other resources.
MAFFS C-130s and a DC-10 Very Large Tanker aircraft, the largest air tanker in the country, carrying retardant also responded.
Fire officials believe the fire was started by a worker trying to cut through a metal fence, which sparked at ignited the dry grass and brush.