DENVER (CBS4) — A pair of small wildfires have drawn the attention of crews in southern Colorado.

Seven aircraft, including one heavy tanker, two helicopters and three single-engine tankers, are flying against the 186 Fire located 11 miles northeast of Durango.

“Fire managers are using retardant drops at the top of the fire to keep it from spreading into steeper terrain above the fire,” the U.S. Forest Service stated Tuesday afternoon in a Facebook post. “A helicopter crew is working the base of the fire to keep it from spreading downhill.”

The fire is believed to be started by lightning, perhaps as early as a week ago when another fire – the 156 Fire – was ignited less than a half mile away.

The 186 Fire is burning Stevens Creek area and no structures are threatened.

In Huerfano County, near Gardner, the Reveille Fire is also burning in remote wilderness. No structures are threatened here, either, and crews are taking a risk-averse approach with more hands crews and fewer aircraft. Almost 250 personnel are involved in the firefight.

Firefighters flew over the fire to get a better assessment of the size and it is now estimated at 75 acres. This photo shows smoke from the fire at 6:30 this morning. #ReveilleFire pic.twitter.com/yorYRobWwk — ReveilleFire (@FireReveille) June 11, 2019

The fire grew by 25 acres Monday and another 25 since Tuesday morning, and now totals an estimated 75 acres in size.

The Reveille Fire was first reported June 3. No cause has been released.

Wildfire Resources

– Visit CBSDenver.com’s Colorado Wildfires section.

Wildfire Photo Galleries

– See images from the most destructive wildfires (Black Forest, Waldo Canyon, High Park and Fourmile), the deadliest (Storm King) and largest wildfire (Hayman) in Colorado history.