As firefighters battled the flames through the night, she walked out of the shrubs toward them, looking for medical help, the statement issued Thursday said.
Law enforcement officers interviewing the woman, whom the district attorney said at a news conference had a lighter in her pocket, later suspected arson.
Smoke has since painted the sky orange as the blaze swallowed homes near the city of Redding.
In Shasta County, which is north of the city and was already hit by a drought, the fire department sent teams out over the weekend to determine how many buildings had burned. They found 131 destroyed structures so far, though that figure was expected to rise with the Fawn fire threatening hundreds more.
Six of the seven largest fires in California’s history have hit since August last year.
With rain expected in the next few days, Cal Fire said calmer weather could help firefighters who have so far reined in just 25 percent of a fire that has so far scorched almost 8,500 acres.
At least 4,000 people have evacuated, with the fire affecting 30,000 residents, the county sheriff’s office said in a statement earlier this week.
Some evacuation warnings have now been lifted. Still, the fire department warned residents in potential danger zones on Saturday to stand ready to leave if the fire picks up near them.