Firefighters appeared to be getting the upper hand on three Utah wildfires Monday, while a fourth blew up on firefighters Sunday and made an uncontrolled run that nearly tripled its size.

A fire on Walsburg Ridge near Deer Creek got away from fire crews Sunday and increased in size to about 600 acres, said Ray Tate of the Interagency Fire Center. Tate said details are sketchy and it is not yet known what caused the fire to explode.Meanwhile, in Emigration Canyon, increased manpower appeared to have made a difference as crews withstood the fire's advance toward two residential areas near the top of the canyon and forced it away from houses.

Officials still consider the blaze out of control, although firebreaks have been secured on the east and south flanks of the fire. They said that should keep it out of the Pinecrest and Killyon canyon areas where most of the threatened homes are located.

Tate said about 1,200 acres burned on Sunday, bringing the total area to 5,400 acres.

Crews have a blaze at Powder Mountain in Weber County about 60 percent contained and hope to have full containment on Monday. If the containment effort succeeds, the 2,400-acre blaze should be under control by Wednesday. That fire has been burning since it was ignited by sparks from a bulldozer Aug. 24.

Crews contained a fire Sunday evening in Fort Canyon near Alpine, Utah County, said Uinta National Forest spokeswoman Loyal Clark.

The 375-acre blaze threatened a residential area for two days but has since moved east away from the homes, allowing fire crews assigned to the residential areas to be moved to locations more strategic to the actual firefighting effort. That fire was ignited by an abandoned campfire in the Sliding Rock area of Fort Canyon.

The fire, which has been burning since Wednesday afternoon, is expected to be controlled Monday, when crews will begin mopping up, said Clark. "All 11 crews will remain in the canyon until the last ember is out.

Forest crews have had problems battling the Fort Canyon blaze. Spot fires spread into a gully. And hornets driven from their habitat attacked a firefighter Saturday. He was taken off the line and treated for multiple stings.

More serious problems have been those caused by humans, Clark said. "This morning (Sunday) we sent out forest officials to scout the area and we found six campfires burning. Of those fires, four were started by people who knew there was a forest closure and that their fires were illegal," she said. "One person just ripped up his ticket and tossed it into the fire."

Most of the major fires burning in the state have been caused by campfires, and the Forest Service is concerned that citizens do not understand the seriousness of disobeying the law, she said.