More than 1,800 acres of Arizona's Tonto National Forest have been burned in the state's first major wildfire of the season. Firefighting efforts on Thursday were hampered by high winds and low humidity.

Winds were expected to reach 40 mph on Friday, up from Thursday's winds of 25 mph. The cause of the blaze was not known.

The fire began at 3 p.m. on Wednesday near Coon Creek and spread quickly, threatening a ranch, an archaeological site and the habitat of the endangered Mexican spotted owl.

A wildfire four years go in the same area ultimately burned 65,000 acres.