Along Arizona's eastern border, a mammoth forest fire is raging uncontained as high winds and low humidity triggered a declaration of emergency to coordinate the entire state's response.

The National Weather Service has issued a 'Red Flag Warning' for southeastern Arizona, most of New Mexico, as well as parts of northern Texas, Colorado and Oklahoma amid critical fire weather conditions.

About half of the 4,000 residents who call Eagar, Arizona home were forced to leave Tuesday afternoon as flames from the Wallow fire overcame the ridges surrounding the area. Residents in the rest of Eagar and in neighboring Springerville grew worried as they awaited word of whether they will have to flee, too.

The blaze has burned 486 square miles of ponderosa pine forest, driven by wind gusts of more than 60 mph, since it was sparked May 29 by what authorities believe was an unattended campfire. Over twice the size of Chicago, the fire has become the second-largest in Arizona history.  It has cast smoke as far east as Iowa and forced some planes to divert from Albuquerque, N.M., some 200 miles (320km) away.

In addition to the back burns overnight, crews Wednesday planned to continue scraping away brush and trees to create a barrier around Springerville and Eagar. More fire fighters and police were expected to descend on the area known as Round Valley on Wednesday.

Thousands of firefighters, including many from several western states and as far away as New York are helping out  and forest supervisor Christopher Knopp said the cost of fighting the Wallow fire has approached $8 million and is rising.

Here's a look at the blaze, the firefighters, and the residents who were forced to flee: