The Wood Hollow Fire, the largest, had spread to more than 45,000 acres in Sanpete County in the center of the state, The Salt Lake Tribune reported. Fire officials said the blaze was about 20 percent contained and would not be fully contained until Monday.
The fire started Saturday with a short-circuit at a utility pole where thieves had stolen copper. At least one person has been killed and evacuation orders for several communities were in place.
The Clay Springs Fire in Millard County, west of Sanpete, had spread to 30,000 acres by Thursday afternoon, fire officials said. The fire began Wednesday afternoon, and Jill Ivie of the Richfield Interagency Fire Center said a combination of high winds, low humidity and plenty of fuel helped its spread.
"We have zero containment. We're using heavy air tankers and single engine tankers and helicopters again to support crews on the ground," she said. "Things were pretty active last night and we did lose one cabin, but our focus today will continue to be protection of homes."
Three smaller fires were burning, The Deseret News reported.
In Carbon County, east of Sanpete, the Seeley Fire had spread to 15,000 acres and was completely uncontained Thursday morning. The blaze, believed to have been caused by a lightning strike, did not threaten any buildings.
The Church Camp Fire in Duchesne County was 5 percent contained, officials said. By Thursday, the fire, which started Sunday, had burned through 6,200 acres.
The Pole Creek Fire, also in Duchesne, was reported Wednesday and was believed to have been started by fireworks. The blaze had spread to almost 1,500 acres Thursday with no containment.