Authorities say an abandoned campfire is likely to have caused the raging "Schultz" wildfire near Flagstaff, the largest of three fires burning in northern Arizona.

The fire has affected at least 10,000 acres of land and forced hundreds of home evacuations.

The blaze started on Sunday and had doubled in size by Monday afternoon.

Dropping fire-suppression chemicals, five helicopters and eight air tankers worked to try to contain the fire alongside the more than 400 firefighters who worked on the ground.

However strong winds, the rocky terrain and dry trees have complicated efforts.

Parts of nearby Highway 89 remain closed to traffic and in the cities of Flagstaff and Corconino County, officials have declared a state of emergency. There have been no reports of injuries so far.

Meanwhile, two smaller fires also continue to burn in northern Arizona.

The Eagle Rock Fire started on June 15 and has burned almost 3,500 acres. The Hardy Fire, which started on Saturday has burned almost 300 acres.