Fire managers were trying to determine the cause of a 10-acre wildfire that destroyed an old abandoned miner's cabin in northern Colorado.
The fire in rugged terrain about 15 miles northwest of Fort Collins set smoke spiraling into the sky after it was reported Monday, as temperatures climbed toward 100 degrees statewide.
About 20 firefighters worked in the heat to fight the blaze with help from two single-engine air tankers and helicopters. About 20 AmeriCorps volunteers were also expected to help, said Reghan McDaniel of the U.S. Forest Service.
On the Western Slope, firefighters battling a stubborn 300-acre wildfire near Delta also faced difficult terrain and searing temperatures.
Crews extended the fire lines to surround 70 percent of the fire on Monday but they could be pulled off the rocky mountainside if lightning strikes increase again.
``We're watching the weather really carefully now because the monsoonal flow coming out of the Southwest will hit us sometime (Tuesday),'' information officer Pam Wilson said.
Through Monday, firefighting costs had climbed to nearly $849,371. Investigators have not yet determined the cause. Nearby houses were no longer threatened, officials said.
Meanwhile, a 60-acre fire that started Sunday in the San Juan National Forest about 12 miles west of Pagosa Springs was 75 percent contained. A Hotshot crew was on the scene, with reinforcements en route, incident commander Steve Hentschell said. No structures were threatened.
A second fire that started June 21 continued to burn at high elevations in the San Juan on Monday. The slow-burning fire, now at 450 acres, was being monitored but not actively fought, fire information officer Randy Moench said.
No structures were threatened, and the fire was considered beneficial to the environment, he said.
The National Fire Information Center said a 1,500-acre blaze in Rio Blanco County in northwestern Colorado was being allowed to burn to clear the forest of dead branches, logs and brush.
