Smoke from a wildfire moves across the sky to the southeast of Eagar, Ariz., Monday, June 6, 2011. Residents in Eagar and nearby Springerville were urged by authorities Monday night to prepare in case evacuations became necessary.

Springerville, Ariz. ? A ferocious wildfire that has driven thousands from their homes in eastern Arizona grew to 486 square miles Tuesday and set its sights on the biggest target yet — two of the most populous towns in the fire-scarred mountains.

The blaze, now the second-largest in state history, began more than a week ago, casting smoke as far east as Iowa and forcing some planes to divert from Albuquerque, N.M., some 200 miles away.

The fire has grown most on the north side, as winds whipped flames through ponderosa pine in the Apache-Sitgreaves National Forest, fire incident command spokeswoman Dellora Guager said.

Winds whipping the fire Monday drove the last holdouts from the small resort town of Greer. At daylight Tuesday, Greer, Alpine and the other tiny resort towns near the New Mexico border were still standing.

No serious injuries have been reported, but the fire has destroyed five buildings.

The future of the towns remained in doubt, as fierce winds were forecast to return later Tuesday. Authorities warned the 7,000 residents of Springerville and Eagar that they may have to join about 2,700 others who have already fled.

The towns are adjacent to the forest in an area called Round Valley.

In preparation for the oncoming flames, firefighting crews are using bulldozers to scrape away vegetation and trees to create, for example, a space between the fire and a home, authorities said.

Crews are also clearing out other combustible sources — such as brush and trees — from outside homes near the forest. Firefighters have also been assigned to protect structures in the towns, fire spokesman Steve Miller said.

“The worst-case scenario is we’re going to order an evacuation and the fire is going to burn up to the homes here. Or to wherever we stand and defend, hopefully not further than that,” Miller said.

Like others in the community on the edge of the national forest, pastor Mike Taylor thanked firefighters, posting a message to firefighters outside the First Southern Baptist Church in Springerville.

He wanted them to know that his parishioners are praying for them.

Taylor said he was ready to evacuate if necessary but was not worried. He said he spent the past week praying. “For me, life is more important,” Taylor said. “Things can be replaced. We just have to trust God is in control.”

The blaze has consumed 311,481 acres since it started May 29. It was aided by wind gusts of more than 60 mph. Fire officials said the blaze died down a bit overnight and crews planned to work on its northeast side Tuesday.

New mapping showed that some fire breaks have held but the wildfire was considered zero percent contained. A giant smoke plume that lingered over Springerville a day ago had dissipated Tuesday morning, leaving behind haze.

The wind, forecast at 35 mph, remained a concern, said fire information officer Kelly Wood.

“It’s going to kick up,” he said.

The evacuation orders in Greer came after most in the community had fled, leaving about 100 people by the time deputies started going door-to-door. Authorities also ordered to leave anyone left in the nearby area known as Sunrise.

“It’s heartbreaking,” said Allan Johnson, owner of Greer’s 101-year-old Molly Butler Lodge, the oldest in the state. He was pessimistic about the chances of saving the lodge and the hundreds of vacation homes in the area.

“We’re numb. Our entire family and our friends are just numb,” he said.

Ashley Stevens, a 24-year-old bartender who has worked at the lodge for a year, was more confident. “They’re done really good in Hannagan Meadow and Alpine, so chances are they could save us too,” Stevens said.

Residents of Eagar are also bracing for a possible evacuation.

“If given the word, then I’m gonna go,” Gerald McCardle told Associated Press Radio. “We’re already packed. We packed last night, and we’re out of here.”

Smoke from the fires was worst in the towns just north of the blaze now ordered to prepare to evacuate.

But haze was being carried by a ridge of high pressure as far as central Iowa, said Kyle Fredin, a National Weather Service meteorologist in Denver. The smoke was also visible in New Mexico, Colorado, Nebraska and Kansas.

Colorado health officials have canceled a smoke health advisory Tuesday as smoke cleared from the southern half of the state. Two airliners headed to Albuquerque were diverted Monday night because of smoke and high winds.

Roughly 2,500 firefighters, including many from several western states and as far away as New York, are working to contain the blaze, fire information officer Peter Frenzen said.

The state’s largest blaze came in 2002 when flames blackened more than 732 square miles and destroyed 491 homes. A fire in 2005 burned about 387 square miles in the Phoenix suburb of Cave Creek and consumed 11 homes.

Another major wildfire was burning in southeastern Arizona, threatening two communities. The 163-square-mile blaze has devoured two summer cabins and four outbuildings since it started May 8.