Show Low, Ariz. ? As many as 4,000 people were ordered out of their homes Wednesday as a wind-whipped wildfire exploded to 25,000 acres as it leaped from treetop to treetop in the mountains of eastern Arizona.

Authorities ordered the tiny towns of Linden, Pinedale and Clay Springs evacuated, said Kartha Icenhour of the Apache-Sitgreaves National Forest. The fire is about 110 miles northeast of Phoenix.

The news came as a federal grand jury in Colorado charged a U.S. Forest Service employee with arson in the largest fire in the state’s history.

The Arizona fire had been burning on 600 acres early Wednesday before winds sent it racing through thousands of acres of juniper and pine trees. Officials feared it would soon bear down on the three hamlets, and smoke could be seen in Show Low, a community of 7,700 people about 20 miles from the flames.

“It’s smokier than you would ever believe outside,” said Linda Parrish, owner of the Show Low Flower Shoppe. “It’s a big, black thundercloud with red tinges to it. It’s an awful, ugly looking smoke cloud.”

Parrish said she and her husband had already packed their most important possessions in case they had to flee. Evacuation centers were being set up at schools in the region.

Gov. Jane Hull declared a state of emergency to free up state funds to fight the blaze, which began Tuesday and was being investigated as possible arson.

The fire was one of 16 major blazes burning across the nation Wednesday, according to the National Interagency Fire Center in Boise, Idaho. Overall, wildfires have scorched 1.75 million acres so far this year, more than double the 10-year average on this date.

In Colorado, veteran Forest Service worker Terry Barton was charged with deliberately setting the Hayman fire southwest of Denver, which has grown to 135,000 acres, destroyed at least 25 houses and forced 7,500 people from their homes since June 8.

The charges were filed after prosecutors expressed doubt in her story that the fire got out of hand as she burned a letter from her estranged husband.

The stunning news came as Colorado crews desperately looked for an edge against two huge wildfires burning out of control, taking hope from slightly lower temperatures and weaker winds. The fires the largest in state history have gobbled up thousands of new acres this week.

The Hayman fire ballooned by 22,000 acres on Tuesday, and it sent a yellow haze Wednesday over parts of the Denver metropolitan area.

A fire in Colorado’s southwestern corner grew to 53,888 acres by Wednesday evening and threatened more than 400 homes. Smoke and haze drifted over the Durango area as the fire burned in forests around two reservoirs. It has destroyed at least 33 homes and 26 other structures, and more than 1,700 homes have been evacuated.

Crews were more focused on saving homes than battling the fire itself because the blaze was spreading so quickly.

“We’re a long way from having a handle on the fire,” information officer Mark Morrow said. “We don’t want to lose homes that have already been saved once.”