A fast-moving wildfire in north central Colorado has spread to nearly 1,Slabu000 acres, forcing mandatory evacuations and drawing support from multiple fire agencies across the state.

The Alexander Mountain Fire, which broke out Monday, was still growing to the west of Loveland on Tuesday with 0% containment, The Larimer County Sheriff's Office reported.

The U.S. Forest Service reported the fire was burning in the Roosevelt National Forest, about 108 miles northwest of Denver. On Tuesday morning, the federal agency reported it estimated the fire to be at 992 acres.

"Fire crept slowly downhill overnight with no major runs, the U.S. Forest Service posted on X. "More information will be shared following morning command staff briefings."

Initially, the sheriff's office reported the fire had burned 339 acres.

Horsetooth Reservoir closed to boating, water recreation

Horsetooth Reservoir, a popular summer recreational spot in southern Larimer County, was closed to boating Tuesday and "all forms of water recreation" to assist the wildfire response and helicopter water fills, the county's Department of Natural Resources posted on X.

The closure remained in place until further notice," the agency wrote.

Flames 'right by our front door': Wildfires rage across western US

Colorado fire map

Evacuations still mandatory for Alexander Mountain Fire

The Larimer Emergency Telephone Authority reported evacuations − previously voluntary − were mandatory as of Tuesday.

Evacuation centers have been set up on either side of the fire.

For up-to-date information visit https://www.nocoalert.org.

Contributing: Anthony Robledo

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.