KACHINA VILLAGE, Ariz. — Hundreds of firefighters worked Thursday to protect communities on the edge of Flagstaff from a wildfire that is chewing up a scenic Arizona canyon with towering flames and burning entire trees down to nothing but ash.
The Slide Fire started Tuesday and had burned more than 11½ square miles in and around Oak Creek Canyon, a scenic recreation area along a highway between Sedona and Flagstaff.
There have been no reports of injuries or structures burned, although the fire grew tenfold from Wednesday and from 7½ square miles earlier Thursday.
Fire incident commander Tony Sciacca said Thursday night that crews have made good progress and some containment was expected to be announced by Friday morning.
The fire still was 3 to 3½ miles away from the residential areas of Forest Highlands and Katina Village, where 3,200 residents remained under pre-evacuation warnings.
Officials were mindful of the fire’s dangers, as they looked at giant flames shooting up the walls of the canyon and saw how hot the fire was burning in the tinder-dry drought conditions.
‘‘The fuels are just so dry, entire trees are turning to ash,’’ said Dick Fleishman, a spokesman for fire managers.
A primary focus of firefighting efforts will be to pinch off the fire where it has reached the top of the canyon’s northeast corner to keep it from burning northward toward residential areas, he said.
Firefighters are also taking extra steps to make sure they don’t lose communication with crews in the steep canyons.
The weather may help even as winds picked up Thursday afternoon with the prospect of higher humidity and a chance of rain by Friday, Fleishman said. However, he warned that thunderstorms could bring rain and moisture to dampen the blaze, but also lightning strikes that could start more fires and powerful downdrafts that could push the blaze erratically in all directions.