The Bureau of Forestry said Sunday it's offering a $5,000 reward for information leading to the arrest of those responsible for setting a pair of blazes Wednesday in the Canadensis area.
The smaller fire was contained over the weekend. But the larger blaze has spread to more than 5,600 acres and burned at least four structures.
The fire has forced the Department of Conservation and Natural Resources to call for an evacuation of a community in Porter Township.
Officials say 160 firefighters are battling the blaze, including a crew from New Mexico known as the Smokey Bear Hotshots.
Authorities say low humidity, rugged terrain and flammable fuel has continued to hamper firefighters' efforts.