A helicopter looks to make a drop of water as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Litteton, Colo. (AP Photo/David Zalubowski) 
A helicopter looks to make a water drop as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Litteton, Colo. (AP Photo/David Zalubowski) 
Emergency vehicles block the roadway as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Litteton, Colo. (AP Photo/David Zalubowski) 
Helicopter looks to make a water drop as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Litteton, Colo. (AP Photo/David Zalubowski) 
Onlookers watch as a helicopter drops water on a ridge as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Littleton, Colo. (AP Photo/David Zalubowski) 
A helicopter collects water from a small lake to use in a drop on a ridge as the Quarry wildfire burns in the foothills near the Ken Caryl Ranch development Thursday, Aug. 1, 2024, southwest of Littleton, Colo. (AP Photo/David Zalubowski)
DENVER | Three wildfires burned in Colorado on Friday near heavily populated areas north and south of Denver, with some 30 structures damaged or destroyed, thousands of people under evacuation orders and human remains found in a destroyed house earlier this week.
The Jefferson County Sheriff’s Office disclosed Friday that a blaze threatening hundreds of homes near Littleton was being investigated as arson.
Karlyn Tilley, a spokesperson for Jefferson County Sheriff’s Office, said the investigation is ongoing and they are using a dog specially trained to sniff out sources and causes of fires. Tilley said just because they suspect the fire was human-caused doesn’t mean it was intentional.
Firefighters were making good progress on the fire despite the steep, rocky terrain and blistering heat, and no houses had been burned, officials said.
The cause and origin of a fatal blaze west of the town of Lyons was being probed by the federal Bureau of Alcohol, Tobacco and Firearms, with specially trained fire investigators from the agency helping local authorities, agency spokesperson Crystal McCoy said.
The area blackened by that fire remained relatively unchanged after it burned five houses.
The largest of the Colorado fires, west of Loveland, grew to 13 square miles after previously burning about two dozen homes and other structures. Its cause is under investigation.
Cooler weather were expected across the region Friday with some scattered showers, before hot dry conditions return for the weekend.