Hotshot crews, air tankers and helicopters on Sunday were battling a fire in Arizona's Tonto National Forest that has grown to more than 4 square miles, while three other fires kept crews busy in other areas over the weekend.

The Sunflower fire, the state's biggest, was first spotted Saturday morning. By Sunday, it had charred about 2,700 acres about 20 miles south of Payson. Billowing smoke could be seen from Phoenix.

Tonto National Forest spokesman David Albo said the fire was moving in a northeasterly direction and primarily toward a wilderness area.

With May temperatures well above average, Arizona land managers have been warning residents that vegetation is dry and the risk of fire is considered to be very high in some areas.

Another fire burning on about 40 acres in the Bradshaw Mountains damaged two buildings and prompted a call for voluntary evacuations Sunday afternoon.

The Gladiator Fire ignited on private land next to the Prescott National Forest, about four miles north of Crown King, and was spreading because of windy conditions, State Forest Division spokesman Cliff Pearlberg told the Arizona Republic.

About 280 people have been assigned to the Sunflower blaze along with six air tankers and four helicopters. Another 14 engines were ordered.

No structures were threatened and the fire hasn't prompted any evacuation orders. Authorities have yet to determine a suspected cause of the fire.

Crews on Sunday were also battling the Bull Flat fire, which was thought to have been sparked by a lighting strike south of the Canyon Creek Fish Hatchery on the Fort Apache Indian Reservation.

The fire was burning brush, grass and dead and down fuels on the reservation and in the Tonto Forest. Flames were most active on its northeastern flank, but no structures were threatened.

By Sunday afternoon, the fire had charred more than 480 acres. It was about 35 percent contained.

East of Prescott, crews were able to contain a 30-acre blaze that had briefly forced the evacuation of 20 homes in the Cherry Creek subdivision. The Yavapai County Sheriff's Office said residents were allowed to return Saturday evening.

The Bureau of Land Management is planning within the next week to implement restrictions to reduce the risk of fire on public lands north and south of Phoenix. The restrictions will prohibit campfires and wood stoves as well as limit smoking to within buildings and enclosed vehicles.