More than 250 personnel from across the Denver metropolitan worked to put out hotspots and flare-ups after the OEM received a 911 call about the fire shortly after midnight Sunday, officials said.
A Red Flag Warning has been issued for the foothills of Larimer County, most of Boulder County, all of Jefferson County and the southwest portion of Douglas County on Monday.
However, the fire is creeping near downtown Boulder and has left many residents anxious, Denver Post reported.
Seven aircraft were active over the fire this afternoon, including two Black Hawk helicopters and two Chinook helicopters. Mike Wagner said the area is used by hikers and by transients for camping, leading authorities to believe the blaze was human-caused.
Emergency officials don't know how the fire started.
For another neighbor, Beth Prehn, it was a phone call from a friend at 5:30 a.m. that alerted her.
Fire fighters spay down dry brush near Settlers Park to try and contain the Sunshine Canyon fire on March 19, 2017. She said she was "optimistic" that her home would be spared.
"I love it. I feel like Boulder does a real good job of protecting the homes".
Evacuated residents can go to the Boulder High School parking lot while a temporary shelter is set up at the East Boulder Community Center.
Fire crews work at extinguishing the wildfire in Sunshine Canyon.
The fire reported around 1:40 a.m. Sunday had burned 30 to 50 acres just a couple of miles from downtown Boulder. Multiple fire agencies are responding to the blaze and numerous roads have been closed as a result of the fire.
"Not a great day to be fighting a fire, that's for sure", Boerkircher said.