The blaze was growing fast due to the heat with low humidity. The winds were gusting at 30 miles-per-hour Friday, down from 40 miles-per-hour Thursday.
Investigators say the Clay Springs fire was preventable, and was human caused, starting on a remote road about five miles south of Oak City.
The exact location hasn't been revealed but it appears the origin is east of 3200 West. Investigators are now searching for the suspects responsible for starting the blaze.
The fire has burned thousands of acres, causing second and third degree burns to two Oak City men. One summer home and three barn-like structures were destroyed.
It was still threatening 75 other homes Friday evening.
With six wildfires burning across Utah, there are limited rescources to fight the Clay Springs fire-the number of personnel was only 85 Thursday. On Friday, the number grew to 200, with aid coming in from as far away as Southern California.
Firefighters manuvered around the fire, working to cut dirt barriers in the earth as at least four air tankers and two helicopters dropped fire retardant from above.
If the Clay Springs fire continues to burn, it will threaten a total of four communities- Nephi, Oak City, Scipio and Mills.
Anyone living in any of these areas may yet be evacuated in the next couple of days.