The Promontory Fire, which started early Sunday morning north of Christopher Creek and spread to the top of the Mogollon Rim by Sunday evening, was human caused.
The blaze is currently about 230-250 acres and is expected to burn through the week.
"Unfortunately it's not going to be a thing we put out in a day," said Gary Roberts, Payson Ranger District Fire Prevention Officer. "It's in steep terrain and real heavy fuels, and this is a time of year we don't have personnel and resources like we do normally during the fire season."
Roberts said the fire is burning north of the Highline Trail, west of See Canyon, near Forest Road 284. Firefighters and bulldozers from the Apache-Sitgreaves National Forest were able to seal off the top of the Rim to prevent the fire's spread to the north.
"We've got the Highline closed until further notice, from the 260 trailhead heading west to Tonto Creek Fish Hatchery Road," he said. "Our strategy is to keep it north of the Highline Trail between Forest Road 284 and the Tonto Creek Fish Hatchery Road."
However, Monday the fire jumped the trail and is in 20 to 30 acres of heavy fuel, according to Roberts.
An announcement will be made shortly about the origin of the fire, Roberts said, but that it appears to be human-caused.
"We brought Forest Service law enforcement officers who are fire investigation officers in to make sure it wasn't something that had come from a prescribed burn the Apache-Sitgreaves was doing up on top," he said.
Approximately 100 firefighters and three helicopters were assigned to the fire. They are working to box in the fire on the east, west and southern flanks using roads, trails and natural terrain features.
Roberts said the area is one that has historically never seen a fire, so the fuel is very dense.
Bray Creek Prescribed Burn
A prescribed burn turned into a surprise burn last week when strong winds helped the fire take off. The Bray Creek Burn, north of the Control Road, east of Camp Geronimo, grew to about 120 acres before firefighters snuffed it out.
"We commenced on the prescribed burn on Monday, and we knew a cold front was coming in," Roberts said. "But the winds were stronger than were predicted."
Despite rumors to the contrary, the fire was never out of control.
"You have your objective (that is to be burned) and then you have your burn block boundary, which is your buffer, so to speak," Roberts said. "The wind blew it bigger than we wanted and gave us fits, so we were concerned. It got a little larger than we wanted it to get, but we were able to keep it within the burn block boundaries."
Roberts reiterated the importance of prescribed burns as a firefighting tool.
"We get such small envelopes of time where we can try to accomplish what we need to accomplish," he said. "So many time the variables aren't right.
"Prescribed fire is a calculated risk, but to not do it is far riskier."