A mountain fire in northern Colorado spread more than 300 acres Monday leading to mandatory evacuations, officials said.

The Alexander Mountain Fire is still growing to the west of Loveland with 0% containment, according to the Larimer County's Sherriff's Office.

The U.S. Forest Service estimated the fire to be at 339 acres as of 2:35 p.m. local time as it spreads through the Roosevelt National Forest, northwest of Denver. Air support has been ordered to battle the blaze north of U.S. Highway 34.

The Larimer Emergency Telephone Authority said the evacuations, which were previously voluntary, are now mandatory.

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

“Voluntary Evacuations ordered for a wildfire near Storm Mountain. Citizens in the area of Waltonia Road, Eden Valley to Sunrise Ranch, and Sylvan Dale to Ellis Ranch please GATHER ESSENTIAL ITEMS AND PREPARE FOR EVACUATION,” a LETA alert reads.

Colorado fire map

Colorado air quality map

US wildfire, smoke map

Contributing: Ignacio Calderon and Rebecca Powell, Fort Collins Coloradoan