Fast-moving wildfires in Colorado swept through suburban areas near Denver on Thursday, prompting the evacuation of tens of thousands of people in Boulder County and burning at least 500 homes, a shopping complex and a hotel, the authorities said.
The wildfires came unusually late in the year for Colorado, where severe drought conditions in recent months have set the stage for such blazes to easily spread.
As the sky above Boulder County turned orange on Thursday, ash swirled in the wind and buildings were engulfed in flames. The local authorities announced evacuation orders for Superior and Louisville, and for some residents of Broomfield and Westminster. All of those communities lie between Boulder and Denver, the state capital.
Traffic was heavy in some areas as residents fled approaching flames.
“It’s really smoky, and there are some areas where it’s been hard to breathe outside, and you can see flames depending on where you’re at in the city,” Emily Hogan, a spokeswoman for Louisville, said on Thursday. “The situation is continuing to evolve rapidly and we want everyone to be prepared to take action, if needed.”
Gov. Jared Polis declared a state of emergency, allowing the state to tap emergency funds and to deploy state resources, including the Colorado National Guard. He said wind gusts of up to 110 miles per hour had pushed the fires with astonishing speed across suburban subdivisions.
“This fire is, frankly, a force of nature,” Mr. Polis said at a news conference on Thursday. “For those who have lost everything that they’ve had, know that we will be there for you to help rebuild your lives.”
The fires started on Thursday morning, officials said, and more than 1,600 acres had burned by the evening. The specific cause was unclear as of early Friday morning.
Though a number of small blazes burned through Boulder County, some converged into two larger ones that state authorities named the Marshall and Middle Fork fires. The Marshall unleashed the most damage.
Sheriff Joe Pelle of Boulder County described the fires on Thursday as a “horrific event.” He said he believed both of the main fires had been caused by downed power lines and said he would not be surprised if there were deaths or injuries. As of Thursday night, only one minor injury had been reported: a police officer who got debris in his eye.
As several communities were warning their residents to prepare to evacuate on Thursday night, the National Weather Service reported good news: The high wind warnings in the Boulder area had all been canceled, even though some gusty winds remained.
The police in Broomfield lifted an evacuation order for the city just before midnight local time. The three communities where evacuation orders were still in place early Friday have a combined population of more than 150,000, including about 116,000 people who live in Westminster.
The fires left thousands of people anxiously wondering if their homes would survive the night, and disrupted essential services across several counties.
Avista Adventist Hospital, a 114-bed hospital in Louisville, said on Thursday that it had evacuated its intensive care units and its emergency department, moving patients to two other hospitals. Staff members were sheltering in place and nearby roads were closed, the hospital said.
And Xcel Energy, a utility company with millions of customers in Colorado and other states, said on Thursday afternoon that high winds had caused outages in the Boulder area. The company said it was also intentionally cutting power in some areas because wildfires had affected its natural gas infrastructure.
As midnight neared, the company said it was ending the controlled outages but that its crews would work overnight and into Friday to restore power to other homes.