EL JEBEL, Colo. (AP) — Colorado Gov. John Hickenlooper promised a full investigation Friday into how people firing tracer rounds at a state shooting range allegedly started a wildfire that has destroyed three homes.

Speaking in El Jebel near the fire, Hickenlooper said ammunition that illuminates the path of fired bullets should not have been used when fire restrictions are in place because of extremely dry conditions.

The fire, one of at least six burning in Colorado, had blackened 8 square miles (21 square kilometers) by late Friday. At least 925 homes were evacuated and containment was listed at zero.

Rain was helping slow two other large Colorado wildfires. One burning near Fort Garland in southern Colorado had blackened 165 square miles (428 square kilometers) and destroyed at least 130 homes. It was 35 percent contained.

Another near Durango in southwestern Colorado had burned 85 square miles (219 square kilometers) and was 50 percent contained.

Tracer bullets and other devices with pyrotechnic charges, like exploding targets, are permanently banned at the Basalt range where authorities say the fire started and other ranges run by Colorado Parks and Wildlife. Wildlife officers patrol the ranges, but they are not typically staffed full-time.

People firing at other public shooting ranges caused two other wildfires in Eagle County in June, the Vail Daily reported . Shooters reportedly targeted dry sagebrush beyond the target area at a federal Bureau of Land Management range near Wolcott, starting a 415-acre fire on June 9. In the other, someone shot at a flammable target at a range in Minturn, starting a small fire that was quickly put out.

Parks and Wildlife ranges in northwestern Colorado were closed Wednesday after the latest wildfire started near El Jebel and Basalt, although discussions had already begun about doing so before the fire started, agency spokeswoman Rebecca Ferrell said Friday.

"We understand the fear, concern, and anger of local residents; we share this frustration and concern with the Basalt community. Participation in shooting sports happens safely every day, and an unfortunate incident like this one shows the importance of respecting the rules and laws regarding the use of firearms," Parks and Wildlife director Bob Borscheid said in a statement announcing the closures.

Other individual ranges have also been closed because of the fire danger in other parts of the state, Ferrell said.