Investigators say the quarry fire was caused by humans

Jefferson County sheriff’s investigators determined the quarry fire near Deer Creek Canyon was started by humans and this week launched an arson investigation into a second wildfire in Colorado.

The causes of three Front Range fires remain under investigation, with local sheriffs soliciting public tips and receiving investigative assistance from state and federal agencies.

Meanwhile, firefighters began controlling those fires Friday, while a fourth broke open in southwestern Colorado, charring more than 2,000 acres.

So far, the four fires have burned more than 27,000 acres and are stretching resources across the state as warm weather worsens fire conditions. Friday evening, the fires killed one person and damaged or destroyed at least 30 buildings, prompting Gov. Jared Polis to deploy the Colorado National Guard.

Thousands of people have been evacuated from homes, although officials in Boulder County have begun reopening some areas threatened by the Stone Canyon fire near Lyons. In Jefferson County, officials advised residents to visit an evacuation center and obtain passes to reenter neighborhoods, though they did not know exactly when residents would be allowed back in.

Dry weather and temperatures in the low 90s during the week, along with dry grass and brush, have accelerated the spread of the fires. Warmer weather caused by climate change is making conditions in Colorado more conducive to fires, data shows.

Two fires, the Quarry and Stone Canyon fires, are believed to be human-caused and authorities have opened an arson investigation.

Jefferson County Sheriff’s Investigator Kevin Bost said the quarry fire near Dear Creek Canyon was likely human caused. However, he did not specify whether investigators believe it was intentional or accidental. He also did not say what evidence investigators found.

Sheriff’s spokeswoman Karlyn Tilley asked Friday afternoon for people who might have helpful home security camera footage or others with tips to call a hotline at 303-271-5612. The sheriff’s office is also being helped by a canine from the Colorado Division of Fire Prevention and Control, which can detect accelerants.

The quarry fire grew 50 acres Friday and burned a total of 480 acres since it started Tuesday evening in Deer Creek Canyon Park above Grizzly Drive, where the trail has several switchbacks. But Tilley said firefighters made progress Friday when they were able to connect a fire line on the east and south sides after bulldozers plowed one side and firefighters on the ground dug a trench in steep, rocky terrain.

Stone Canyon fire investigators are getting help from the U.S. Bureau of Alcohol, Tobacco and Firearms to determine the cause of the fire, which has burned 1,553 acres near Lyons.

Nathan Hallam, Stone Canyon’s fire incident commander, said in a briefing Friday afternoon that crews had contained 53% of the fire and hoped it would be fully contained by Sunday.