The Gann Fire burns along a hillside near Copperopolis on Tuesday, Aug. 4, 2026, in Calaveras County, Calif.

Cal Fire officials believe they have uncovered the cause of the Gann Fire, currently the largest active fire in the state. Law enforcement officers with Cal Fire arrested 65-year-old Herbert Wayne Smith of Valley Springs on suspicion of igniting the fire, which has scorched more than 10,000 acres.

Smith was arrested on Monday, the same day the fire started near New Hogan Lake, which is just a few miles from Valley Springs.

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Smith allegedly violated the California Public Resources Code by using equipment that could spark without properly clearing out vegetation at risk for catching fire. He was also found to be in violation of letting a fire escape........

© SFGate