FILE - The U.S. Forest Service shows a helicopter fighting a wildfire in Coconino National Forest in Arizona, April 30, 2018. Visitors at the park have been asked to evacuate after a fire in the state grew to more than 400 hectares on July 22, 2019.
FILE - The U.S. Forest Service shows a helicopter fighting a wildfire in Coconino National Forest in Arizona, April 30, 2018. Visitors at the park have been asked to evacuate after a fire in the state grew to more than 400 hectares on July 22, 2019.

A wildfire in the western U.S. state of Arizona grew from 80 hectares to more than 400 hectares overnight, officials said Monday. 

Residents of the city of Flagstaff and surrounding communities have been warned to expect heavy smoke to stifle the area. Campers and visitors to the Coconino National Forest have been asked to evacuate.

Some 200 firefighters and a dozen aircraft, including four air tankers, have been fighting the blaze, dubbed the Museum Fire. 

The cause of the fire, first reported Sunday morning, is under investigation.

Arizona Governor Doug Ducey said his office was in contact with emergency responders.

"My thoughts and prayers are with the firefighters and first responders working to protect Arizonans, their pets and their property," a statement released by his office said.