Golden, Colo. (KKCO) - Jefferson County officials said one wildfire west of Golden had charred a little more than a square mile, or 850 acres, or rugged, steep terrain, with crews periodically retreating when winds kicked up.

A grass fire of about eight acres was threatening at least 25 homes near Evergreen, roughly 20 miles southwest of Golden, while a third, smaller fire in the mountains west of Denver destroyed a structure before it was contained.

Crews had contained 30 percent of the Evergreen fire by evening.

Officials suspect the blazes were human-caused.

Low, single-digit humidity and dry vegetation had helped fuel the fires Monday while many areas across eastern Colorado were under red-flag warnings, meaning the fire danger was high and some counties had fire bans.

All outside fires were banned in unincorporated parts of Jefferson County and on Federal land.

Evacuation centers have been opened at a church in Golden and Evergreen High School.