More than 100 firefighters are now battling the Big Red Fire along the Colorado/Wyoming state line.
It has spread rapidly over the past few days, growing to about 800 acres on Labor Day,
By Tuesday it had spread to more than 1,400 acres.
PREVIOUS STORY: ‘Extreme' fire burning near Wyoming border
The Big Red Fire sparked from a lightning strike on Aug. 19.
The fire is burning five miles south of the Colorado/Wyoming state border, 45 miles north of Steamboat Springs, three miles west of the Mount Zirkel Wilderness.
That is located just north of Big Red Park along Forest Road 500.
The fire is active with running, spotting, and group torching according to the latest update.
Beetle-kill conifer trees are burning primarily in the Big Red fire's path. Continued hot and dry weather with the chance for more thunderstorms has firefighters pretty concerned about its spread over the coming days.
The fire is burning in the Routt National Forest.
© 2017 KUSA-TV