Fire officials say the nearly 17-square-mile Squirrel Creek Fire about 30 miles southwest of Laramie was human-caused.
Fire spokesman Larry Helmerick says an investigation is continuing.
The fire was 55 percent contained Thursday. Fire managers hope to fully contain it Saturday night.
Fifteen homes were evacuated Wednesday because the fire grew to the southeast in beetle-killed timber. However, rain fell at the fire and crews made progress against the fire overnight.
Residents previously evacuated on the east side of the fire were able to return home Wednesday.
Air Force C-130 cargo planes have been used to drop slurry on the blaze, which has destroyed one home and three outbuildings.
Crews continue to fight the Fontennelle fire in the Bridger-Teton National Forest and the 91-square-mile Oil Creek fire in northeastern Wyoming.