ST. GEORGE — Two juveniles are suspected of starting a wildfire that has consumed 22,068 acres of brittle grass and dry pinyon-juniper shrub about 10 miles west of here.

"Two 16-year-olds were out on motorcycles and horsing around with matches," Washington County Sheriff Kirk Smith said Monday afternoon. "They (fire officials) do know who it is."

The fast-moving Apex fire jumped Old Highway 91 near the Shivwits Indian Reservation, prompting the voluntary evacuation of 14 homes on the reservation late Sunday evening. Those people spent the night at a local high school after Red Cross officials set up cots and other supplies for them.

"The fire came really close and burned with such intensity it was kind of scary," said Smith. "There wasn't even any stubble left on the ground."

David Boyd, fire information officer with the Bureau of Land Management in St. George, said the fire doubled in size overnight to 12,289 acres.

Gusty, high winds coming from the southwest swept the area on Monday.

"We're building a fire break around the homes that were evacuated," said Boyd. "We're coordinating everything closely with the local fire departments so there's no imminent danger of fire threatening structures."

A Type 2 fire management team took over firefighting efforts at noon on Monday. Five new firefighting teams of 25 people each arrived to relieve the 120 firefighters that were on duty since Saturday morning when the fire was reported.

"Our strategy now is to get those breaks in around the radio towers on Utah Hill. Crews are working on securing that area," Boyd said. Crews will check the eastern flank of the fire on Tuesday to makecertain no hot spots remain.

Fire crews from Santa Clara and Ivins managed to beat back flamesthat threatened the OMB Apex facility, said Smith.

Old Highway 91 between the reservation and the Nevada line remains closed for now. Deputies also closed the road between Veyo and Gunlock.

Crews battling two other Southern Utah blazes remain confident in their plans to snuff the fires.

In Finn Canyon, 18 miles west of Price, crews had the 100-acre fire 90 percent contained Monday evening, after spending most the day dousing several hot spots, said Becky Barrett of the Moab Interagency Fire Center.

Crews used large buckets strung on to helicopters to pour water from nearby Scofield Reservoir over the fire. And 108 firefighters and personnel are on the ground. Lightning ignited the blaze Friday, Barrett said.

The Wooden Shoe fire in the Dark Canyon Wilderness Area of the Abajo Mountains 25 miles west of Blanding grew to 750 acres Monday night.