Officials in Arizona reported the so-called “Tunnel Fire” doubled in sized overnight to 26 square miles by Wednesday morning. According to the National Wildfire Coordinating Group’s (NWCG) InciWeb Incident Information System, the fire was reported Sunday afternoon “approximately 14 miles northeast of Flagstaff.”

“Cause is unknown but currently under investigation,” the NWCG said. “The fire is located in an area with dry grass and brush, with scattered Ponderosa pine. Windy conditions caused this fire to rapidly spread in a northeast direction.”

Wind gusts of up to 50 mph pushed flames as high as 100 feet over a major highway Tuesday. The Tunnel Fire was headed toward Arizona’s Sunset Crater Volcano National Monument, but away from the city of Flagstaff itself.

“It’s good in that it’s not headed toward a very populated area, and it’s headed toward less fuel,” Coconino National Forest spokesman Brady Smith said. “But depending on the intensity of the fire, fire can still move across cinders.”

Weather conditions were more favorable Wednesday with light breezes. However, stronger winds are expected to return Thursday.

“The National Weather Service (NWS) in Flagstaff has issued a Fire Weather Watch due to strong winds and low relative humidity, which is in effect from Thursday morning through Thursday evening,” NWS said Wednesday morning. “The combination of gusty winds and low humidity can cause fire to rapidly grow in size and intensity before first responders can contain them.”

During a Tuesday evening news conference, Coconino County officials said 766 homes and 1,000 animals had been evacuated. About 250 structures remained threatened after a couple dozen structures were already damaged.

Authorities won’t be able to determine whether anyone was injured in the Tunnel fire until flames subside. However, Coconino County Sheriff Jim Driscoll did say his office got a call about a man who was trapped inside his house. Firefighters couldn’t get to him.

“We don’t know if he made it out,” Driscoll said.

Elsewhere in Arizona, firefighters have battled but so far have yet to contain the Crooks Fire in the Prescott National Forest. The National Interagency Fire Center reported Wednesday over 2,300 wildland firefighters and support personnel were assigned to more than a dozen large wildfires in the Southwestern, Southern and Rocky Mountain areas. In addition, red flag warnings blanketed much of New Mexico on Wednesday, indicating conditions are ripe for wildfires.