The Doce fire outside Prescott, Ariz., had expanded to 7,000 acres, The Arizona Republic reported. High winds and arid conditions fanned the flames with the smoke blowing toward Prescott, the state's third-largest city.
A number of homes in the area 100 miles north of Phoenix were evacuated Tuesday with other residents put on notice that they might have to leave, officials said. A shelter was set up at Yavapai College in Prescott with livestock given a temporary home at the Prescott Rodeo Grounds.
In California, officials said it would take several weeks before the area burned by the Carstens fire in Mariposa County in the Sierra foothills will be safe to enter.
The fire, declared 40 percent contained, had burned nearly 2,000 acres but no structures had been damaged, the Mariposa Gazette reported Wednesday.
Some of the more than 1,000 residents ordered to evacuate their homes were being allowed to return but the Jerseydale/Mariposa Pines residential area remained under an evacuation order.
The Mariposa County Sheriff's Office said all agencies are working hard to get everyone back home as quickly as possible.
About 500 residences were still threatened by the fire, the California Department of Forestry and Fire Protection said.
A department spokeswoman said the wildfire that began Sunday night was started by an unattended campfire, the San Francisco Chronicle reported.
"They are investigating if anyone was camping there or anyone knew who was camping there," spokeswoman Karen Guillemin said.