Mass evacuation ordered, emergency declared in eastern Arizona flooding

The Southwest's dangerous flooding Monday overwhelmed the Old West town of Duncan, prompting "mass evacuation" and a local state of emergency.

The "mass evacuation of flood prone areas in Duncan" was declared early Monday by the Duncan Valley Rural Fire District, which listed more than a dozen streets in the 712-person town as subject to the order.

Mayor Anne Thurman declared the state of emergency shortly after noon.

She cited rainfall since Aug. 15, dangerous flooding and "extreme peril to life and property," according to the declaration.

Thurman formally asked the state for first responder resources.

In an afternoon update, the town said new concerns about the integrity of a century-old river levee that had been breached earlier Monday means that evacuees should continue to stay away.

The Gila River, which runs through town on its journey from Gila National Forest in New Mexico to the Colorado River in Yuma, crested after 7 a.m. at 2.5 feet above what's considered its flood state, federal forecasters said.

Images obtained by NBC News showed the river encroaching on the town as floodwaters took over some streets and a gas station, where the ground was covered in a shallow layer of still water.