A wildfire that destroyed two homes and threatened dozens of others appears to be the work of an arsonist who has set 10 other fires in central Washington in the last two months, authorities said Saturday.

A state of emergency was declared in Kittitas County (search) as a wind-swept blaze forced the evacuation of dozens of homes in the Cascade foothills. Helicopters dropped water and planes distributed retardant to prevent the fire's spread.

"We are investigating this fire as arson," Undersheriff Clayton Myers said Saturday. "We believe they are all linked."

Myers said the blaze destroyed two homes and a shop as it raced across 300 acres. None of the previous 10 arsons in Kittitas County damaged buildings.

About 100 homes remained evacuated Saturday. By evening, the fire was holding at about 600 acres, said Cindy Reichelt, an incident information officer. Fire officials did not have a containment estimate.

The fire began Friday near Interstate 90 between Cle Elum (search) and Ellensburg. Some of the homes firefighters were able to save had flames lapping at the front door, Myers said.

"It's stressing our resources. In fact, we've moved beyond what our resources can handle," Myers said.

High winds posed a threat as firefighters hoped to channel the fire away from nearby timber, said Dave Johnson, incident commander for Washington state.

"There's a lot of fire still in the trees. Where the wind goes is where it's going to take it," Johnson said.

Amber Schlichting, 20, cried when she heard the news Saturday: Her family's home was one of two destroyed in the wildfire that roared through a nearby canyon a day earlier.

"I still just can't believe it. They tell me everything's gone," Schlichting said. "It doesn't even feel like reality."

Most of the recent arsons have been set in the afternoon, in areas with plenty of fuel, such as dry grass or timber, and near homes and highway access.

The sheriff's department offered a $10,000 reward for information in the case.

In southwestern Utah, a pair of lightning-caused fires, fanned by hot winds and low humidity, consumed a combined total of nearly 38,000 acres.

The fires were in a part of Dixie National Forest (search) where prescribed burns had been planned, but firefighters started working to suppress the larger blaze Saturday after it came within a mile of the farming community of Enterprise. Backfires stopped its advance, fire information officer Maggie Dowd said.

Occupants of eight homes evacuated voluntarily, although fire officials said no structures were threatened.

Meanwhile, in Nucla, Colo., a wildfire burned 3,800 acres near the Utah state line Saturday and officials were worried a heat wave would make it tough to fight as well as bring on more fires.

Several hundred head of cattle and several trailers and structures were threatened.