Three people are missing and presumed dead after a wind-fueled wildfire raged across two communities in Boulder County, Colorado, authorities said on Saturday, forcing thousands of residents to evacuate and destroying almost 1,000 homes.

Officials initially stated that no fatalities or missing individuals had been reported due to the uncommon urban wildfire that started Thursday morning on the northern fringes of the Denver metropolitan region.

Wind gusts of more than 100 miles per hour (160 kilometers per hour) carried flames eastward towards the towns of Superior and Louisville, forcing both communities to evacuate.

The fire destroyed 6,000 acres in approximately two hours, officials said.

Sheriff Joe Pelle of Boulder County said the three missing people he declined to identify all lived in homes destroyed by the blaze.

"The structures where these people would be are completely destroyed and covered in about eight inches of snow," Pelle said during a Saturday news briefing, adding that cadaver dogs will be dispatched to investigate the houses on Sunday.

According to Pelle, 991 properties in Superior, Louisville, and unincorporated areas of the county have been burned, making it the state's most damaging wildfire in terms of residences destroyed.

Initially, officials speculated that sparks from downed power lines caused the incident. Still, an assessment by utility company Xcel Energy revealed no damage or downed lines near the fire's suspected origin.

Pelle stated that police are looking into all possible causes of the conflagration. The sheriff noted that a search warrant was issued in conjunction with the investigation after receiving a tip but declined further details.

According to the Federal Emergency Management Agency, President Joe Biden of the United States proclaimed the situation a national disaster, allocating federal cash to assist affected residents and businesses with recovery efforts.