The Grizzly Creek fire burning outside Glenwood Springs is under 4% containment as of Wednesday, according to the U.S. Forest Service.

The fire, which was the state’s highest priority fire over the past week, burned more than 28,000 acres in forests near Interstate 70.

More than 800 firefighters along with 17 helicopters worked to set up containment lines and were able to report the first percentages of containment Wednesday.

Roads and natural barriers helped fire firefighters make headway on containing the fire, according to Mary Cernicek, spokeswoman for the Grizzly Creek Fire. The fire’s slowing pace also helped as it spread into a different type of vegetation — Aspens, which Cernicek said burn slower than conifer trees.

“They’re doing some significant work,” Cernicek said about the firefighters. 

But weather is still a major concern for firefighters as dry lightning and strong winds are possible amid thunderstorms in the next few days.

Thunderstorms pose significant danger because winds can quickly change the direction the fire is burning, she added.

Firefighters continue to protect structures in the area and Interstate 70 remains closed between Gypsum and Glenwood Springs.

The state’s second-highest priority fire is the Williams Fork Fire burning in the Arapaho National Forest.

The blaze encompassed 6,726 acres as of Wednesday afternoon and was 3% contained, according to the U.S. Forest Service.

There are no evacuations issued although a Red Flag Warning was issued cautioning firefighters because of the dry fuel conditions, including timber understory vegetation, and the weather predictions of strong gusts of winds.

Farther northwest of Fort Collins, the Cameron Peak fire is raging at 15,738 acres and is still zero percent contained.

Winds from thunderstorms are also expected to exacerbate the spread of its smoke and flames. 500 firefighters responded to the blaze along with 10 helicopters. There are several road closures but no structures have been damaged.