Three people are missing and feared dead after a wind-stoked wildfire roared through two towns in Boulder County, Colorado, prompting thousands of evacuations and destroying nearly 1,000 homes, authorities said on Saturday.
Officials initially said there were no reports of fatalities or missing residents following the rare urban wildfire that erupted Thursday morning on the northern outskirts of the Denver metropolitan area.
Wind gusts in excess of 100 miles per hour (160 kph) pushed flames eastward into the towns of Superior and Louisville, prompting the evacuation of both communities.
In about two hours, the fire had scorched 6,000 acres, officials said.
Boulder County Sheriff Joe Pelle said the three missing people, whom he declined to identify, all lived in homes that were consumed by the blaze.
"The structures where these folks would be are completely destroyed and covered with about eight inches of snow," Pelle said at a Saturday news briefing, adding cadaver dogs will be deployed on Sunday to search the dwellings.
Pelle said 991 homes in Superior, Louisville and in unincorporated parts of the county have been destroyed, making it the most destructive wildfire in state history in terms of residences lost.
Officials initially said sparks from downed power lines that were toppled by the gale-force winds may have sparked the blaze, but an inspection by utility company Xcel Energy found no damaged or downed lines near the fire's believed origin.
Pelle said detectives are investigating all avenues to determine what ignited the conflagration. Acting on a tip, the sheriff said a search warrant was issued in connection to the probe, but declined to offer any details.
U.S. President Joe Biden has declared the scene a national disaster, freeing up federal funds to assist affected people and businesses in recovery efforts, the Federal Emergency Management Agency said in a statement.