[10] Effects of the high winds were also observed on the University of Colorado Boulder campus, where downed branches and trees were reported.

He said that the fire was caused by two separate occurrences: "week-old embers on Twelve Tribes property and a sparking Xcel Energy power line," adding that negligence and intent had been ruled out and no criminal charges were expected.

By noon the fire had reached the town of Superior, three miles (4.8 km) to the east, prompting the evacuation of stores there.

[19] Within another hour evacuations had been ordered for tens of thousands of people starting with the town of Superior and later the cities of Louisville, portions of Broomfield, and unincorporated Boulder County.

In response to the fires, Governor Jared Polis declared a state of emergency around 3:15 p.m. on the day of the outbreak and ordered a ground delay at Denver International Airport.

[1][3] U.S. president Joe Biden responded to the fire by permitting the Federal Emergency Management Agency to assist.

[11] Safety warnings were also issued for travelers on a stretch of Interstate 70 between Golden and Georgetown and Colorado State Highway 93 was temporarily closed for 40 minutes in the late morning.

[11] An estimated 1,084 structures, including houses, a hotel and at least one shopping center, burned as a result of the Marshall Fire, and another 149 were damaged.

[citation needed] The Marshall Fire exposed people to dangerous airborne compounds through ash and smoke.

A research paper published in 2025 reported that people living near the burned areas self-reported a heightened frequency of headaches, sore throats, and coughs compared to control populations.