Since a series of wildfires started across Colorado last Monday, fire crews have managed to hold or increase containment on four and fully extinguish one.

The fires in Larimer, Boulder, Montrose and Jefferson counties have together killed one person, damaged or destroyed more than 50 buildings, evacuated thousands of people and charred approximately 15,000 acres.

All of the fires grew rapidly, fueled by hot, dry weather and arid conditions on the ground.

After fully extinguishing the Lake Shore fire last week, Boulder County officials announced Sunday that fire crews had fully contained the Stone Canyon fire. Flames could continue to burn in the contained area for days or weeks.

The three remaining wildfires -- the Quarry fire in Jefferson County, the Alexander Mountain fire in Larimer County and the Bucktail fire in Montrose County -- continue to grow as fire crews fight to contain them.

As of Monday night, the Quarry fire burning on more than 500 acres of land in Jefferson County was 45% contained, fire officials said.

The 537-acre fire, which forced nearly 600 homes to evacuate after it started burning late July 30, has not destroyed any structures.

The wildfire's footprint grew slightly on Monday because of controlled burning to increase containment along the western edge, according to sheriff's office spokesperson Karlyn Tilley.

On Monday, a helicopter dropped small spheres across the area that contained a mix of chemicals and ignited 30 seconds after impact, according to West Metro Fire Rescue. The small, controlled flames were able to remove vegetation and loose debris from the area that would have fueled the fire's spread.

Combined with firefighters hand-burning areas on the ground, crews were able to burn potential fuel sources and secure and strengthen the containment lines, fire officials said.

"The helicopter was able to get to areas that would be very difficult and dangerous for firefighters to access, considering the steep, rocky terrain," fire officials said.

The Deer Creek Mesa and Kuehster neighborhoods are no longer under a mandatory evacuation order and are back on pre-evacuation. Only residents with credential cards for those neighborhoods will be allowed in. All road closures remain in place.

The Sampson, Maxwell, McKinney Ranch and Murphey Gulch subdivisions remain under mandatory evacuation orders, and the Silver Ranch, Jennings, Homestead, Oehlmann and West Ranch neighborhoods are on pre-evacuation status.

No details about the ongoing arson investigation were available Tuesday morning. Anyone with information about how the fire started can call the Quarry fire Tip Line at 303-271-5612.

Last updated at 9:23 a.m.

Fire crews gained 74% containment on the 9,668-ace Alexander Mountain fire Monday, and the lines continued to hold Tuesday morning.

The fire, which sparked on Monday, July 29, is burning in the Roosevelt National Forest and on private land 10 miles west of Loveland.

As of Tuesday, 26 homes and 21 outbuildings had been destroyed in the Storm Mountain and Cedar Park areas, and four more homes were damaged.

Larimer County Sheriff John Feyen said it's possible that more damaged or destroyed structures will be found, and the Larimer County Office of Emergency Management has contacted people with known damage to structures to provide resources and next steps.

The cause of the wildfire remains under investigation Tuesday morning. Feyen said Monday that investigators found signs of human activity and multiple lightning strikes at the place it started.

Anyone with information can call the Forest Service Law Enforcement Tip Line at 303-275-5266.

Last updated at 7:40 a.m.

The Bucktail fire burning on more than 3,700 acres of land near Nucla in Montrose County is 7% contained Tuesday.

The fire was first reported on private land on Aug. 1 and quickly grew to nearly 2,000 acres. By Tuesday, the fire had charred 3,738 acres.

The fire is burning in pinyon pine, juniper and brush oak and has spread to U.S. Forest Service and Bureau of Land Management lands in Uncompahgre National Forest, according to a map from fire officials.

The cause of the fire remains under investigation.