Three men who were working in a hay field died after being overcome by a wildfire burning in eastern Utah.

The three men and the son of one of the victims were working in the field Friday afternoon when they were caught in the fire after it suddenly changed direction. The 11-year-old boy escaped, but his father and grandfather died in the field.

A 75-year-old man was flown to Salt Lake City, where he died overnight, Uintah County Sheriff Jeff Merrell said Saturday.

"A fire wall came over that hill," Merrell told the Deseret Morning News. "The officers who were here said it just started sucking up all the air."

The boy was treated and released from Uintah Basin Medical Center in Roosevelt, about 15 miles southeast of Whiterocks.

Trevor Quick, a friend of the family, said the men apparently told the boy to run and he was able to escape.

Merrell identified two of the victims as 63-year-old George Houston and his son, 43-year-old Tracy Houston, 43. Roger Roberson, 75, died later at University Hospital in Salt Lake City, spokesman Chris Nelson said.

The fire started north of Neola, about 100 miles east of Salt Lake City, on Friday morning and burned more than 14 square miles in less than a day. By Saturday afternoon, about 23 square miles, including part of Ashley National Forest in the northeastern corner of the state, had been consumed.

Gov. Jon Huntsman requested aid from the Federal Emergency Management Association after being flown over fire area.

"He said this is a very frightening scene. It's a serious fire and we need to do everything we can to help these people," said Lisa Roskelley, the governor's spokeswoman. "It really is going to be a long-term fire as well."

Heavy smoke blanketed the horizon north of Neola, just west of the Duchesne and Uintah county line.

Extremely dry conditions and strong wind fueled the fire, which had reached the southern edge of Ashley National Forest and was consuming brush, juniper and pine. Wind gusts Saturday were expected to reach up to 25 mph, fanning the flames even more.

"We're seeing some short runs in cheatgrass and pretty aggressive fire behavior," said Louis Haynes, a spokesman for the Uintah Basin Interagency Fire Center.

The cause was still unknown Saturday as crews tried to contain the fire.

A specialized team of about 60 firefighters had been called in and was expected to take over fighting the blaze first thing Sunday morning.

Conditions for wildfires to spread rapidly are high throughout the state because of a dry spring and very dry early summer. Once a fire starts, it spreads very quickly across the parched mountain valleys.

The most recent fatality in a Utah wildfire was last summer, when a Bureau of Land Management firefighter was trapped as shifting winds fueled flames burning in the Fishlake National Forest.

BLM officials couldn't immediately say when a civilian last died in a wildfire in Utah.