Wildfire in northern California

Firefighters watch the Rocky Fire advance in Lake County, California July 30, 2015. REUTERS/Max Whittaker

The Rocky Fire burns through a fence line in Lake County, July 30, 2015. REUTERS/Max Whittaker

Firefighters race to battle a spot fire at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

A helicopter drops water on the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

A Cal Fire firefighter races to move a truck before it's overrun at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

A firefighter battles a spot fire at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

Swirling winds blow debris at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

Lassen National Forest Service Assistant Fire Engine Operator Adam Giordano drags a hose up a fire line at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

Firefighters on the ground and in the air scramble to battle spot fires at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

Firefighters work to dig a fire line on the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

A bulldozer battles a spot fire at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

Firefighters battle a spot fire at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker

An oak tree ignites at the Rocky Fire in Lake County, California July 30, 2015. REUTERS/Max Whittaker

A helicopter drops water on the Rocky Fire in Lake County, California July 30, 2015. REUTERS/Max Whittaker

A firefighter watches for spot fires at the Rocky Fire in Lake County, July 30, 2015. REUTERS/Max Whittaker