GREELEY, Colo. — A fast-moving grass fire in Greeley killed one person and critically injured another Saturday afternoon as authorities investigate whether a microburst that damaged power poles in the area played any role in the blaze.

The 15-acre fire broke out near the interchange of U.S. 34 and U.S. 85 and was spreading across several acres of open land near unhoused encampments. Crews from the Greeley Fire Department responded to the area around 1:39 p.m.

During the response, emergency personnel found a 45-year-old woman dead in the burn area and a 48-year-old man critically injured. The man was airlifted to a Denver hospital for treatment and is listed in critical condition. It's unclear if the two victims were associated with the encampments.

Firefighters faced additional challenges due to live Xcel Energy power lines near the scene. However, crews were able to get the fire under control later that day.

Authorities investigate whether microburst played role in deadly Greeley fire

Xcel Energy told Denver7 that a microburst struck the area around the time of the fire, damaging power poles and leaving more than 3,500 customers without electricity. Service was restored later Saturday evening, according to the utility.

Authorities have not determined what sparked the blaze. A Greeley Police Department detective and the Greeley Fire Department's arson division are jointly investigating the fire's cause and origin.

The name of the deceased will be released by the Weld County Coroner's Office pending notification of next of kin. Anyone with information on this case is urged to contact Detective Max Moree at Max.Moree@greeleypd.com.

No additional details were released Sunday.

Storm causes damage elsewhere in Weld County

Meanwhile, in northern Weld County, a microburst struck the Ault Fall Festival in the town of Ault Saturday afternoon, sending debris flying and injuring one person, who was taken to a hospital with non-life-threatening injuries.

The storm caused enough damage that festival organizers suspended the event permit and canceled Saturday night's activities. Flying debris and damage were also reported at a nearby mud volleyball event, though no injuries were reported there.

According to the National Weather Service, a microburst is a powerful, localized downdraft capable of producing damaging winds over a relatively small area.

It forms when a thunderstorm's updraft can no longer support large amounts of rain and hail suspended high in the storm, creating a powerful downdraft that spreads outward in all directions when it hits the surface.

The location in which the microburst first hits the ground experiences the highest winds and greatest damage, according to the NWS.