DENVER (AP) - Mike Guanella and his family were relaxing at their Colorado home and looking forward to celebrating a belated family Christmas later Thursday when reports of a nearby grass fire quickly turned into a concerning pre-evacuation notice and then within minutes into an order to leave immediately.

The Guanellas were among tens of thousands of residents who were forced to evacuate their homes outside Denver as wildfires fueled by winds that gusted up to 105 mph engulfed parts of two cities and burned an estimated 580 homes, a hotel and a shopping center.

Instead of opening Christmas presents at home in the city of Superior as they had planned, Guanella and his wife, their three children and three dogs were staying a friend’s house in Denver and hoping their house was still standing.

“Those presents are still under the tree right now … we hope,” Guanella said.

At least one first responder and six others were injured in the fires that began Thursday morning, unusually late in the year and following an extremely dry fall and a winter so far nearly devoid of snow. Boulder County Sheriff Joe Pelle acknowledged that more injuries and also deaths could be possible due to the intensity of fires that quickly swept across the region.

“This is the kind of fire we can’t fight head on,” Pelle said. “We actually had deputy sheriffs and firefighters in areas that had to pull out because they just got overrun,” he added.

As night fell, officials were watching how the winds behaved and the fires reacted to determine when crews are able to go in and begin assessing the damage and searching for any victims.

Evacuations were ordered earlier in the day for the cities of Louisville and Superior, located about 20 miles northwest of Denver and home to a combined 34,000 people. A nearby portion of U.S. Highway 36 also was shut down.

The neighboring towns are filled with middle and upper-middle class subdivisions surrounded by shopping centers, parks and schools. The area is in between Denver and Boulder, a foothills college town home to the University of Colorado.

Residents evacuated fairly calmly and orderly, but the winding streets in the subdivisions quickly became clogged as people tried to get out. It sometimes took cars as long as 45 minutes to advance about a half mile.

Small fires cropped up here and there in surprising places - on the grass in a median or in a dumpster in the middle of a parking lot - as wind gusts caused the fire to jump and spread. Shifting winds caused the skies to turn from clear to smoky and then back again as emergency sirens blared nearby.

One video captured by a bystander outside a Superior Costco store showed an apocalyptic scene with winds whipping through barren trees in the parking lot surrounded by gray skies, a hazy sun and small fires scattered across the ground.

Pelle said the first fire erupted just before 10:30 a.m. and was “attacked pretty quickly and laid down later in the day and is currently being monitored” with no structures lost.

A second wildfire, reported just after 11 a.m., “ballooned and spread rapidly east,” Pelle said. The blaze spans 2.5 square miles.

Some of the blazes in the area Thursday were sparked by downed power lines.

The fires prompted Gov. Jared Polis to declare a state of an emergency, allowing the state to access disaster emergency funds.