A wildfire that started Saturday along the Highline Trail had burned more than 80 acres by Tuesday morning.
U.S. Forest Service officials suspect the fire was started by elk hunters in the area.
Dan Eckstein, acting fire manager for the Payson Ranger District, said investigators are still searching for information that will lead to the cause of what forest officials have dubbed the Elk Fire.
Eckstein said the fire started at 3 p.m. Saturday and continues to burn in the old Dude Fire area, burning brush, pine snags, blown-over trees and 3-foot-high matted grass.
Eckstein said the fire should be contained by Thursday night.
"What our strategy is," Eckstein said, "is keeping above Highline Trail, west of Myrtle Point and east of Elephant Creek."
The terrain is steep and rocky, and firefighters have been forced to fight the fire from a distance.
"We're not cutting line directly around the fire edge," Eckstein said. "The reason for that is there are rolling rocks and steep terrain. It's holding on a real rocky ridge coming off the Rim."
A lot of the regular firefighters are on leave at this time of the year, he said, and crews have been called in from Payson, Globe, Tonto Basin, Cave Creek and Pleasant Valley.
"The fuels right now are as dry as the end of June," he said. "We have had no rain since Sept. 23."
An air attack plane has been called out and is flying reconnaissance missions every two hours.
Although the Highline Trail hasn't been closed, Eckstein recommends that people stay away from the Highline Trail.
He said another wildfire started Monday north of Diamond Point, but has only burned about an acre. Investigators think that fire also was human caused, possibly by a cigarette, Eckstein said.
"We're expecting containment on the Elk Fire (later this week)," Eckstein said Monday. "There's nothing out there, no structures. A lot of the fire is stopping at natural barriers.
"Until we get rain or snow, people need to be really careful. The only thing that helps is that the days are short and there are cooler temperatures. We're running a very high fire danger. We've had a few dry Decembers, but it's pretty rare that it's this dry."