AP: California’s largest wildfire was started by hammer sparks

California fire officials say sparks from a hammer driving a metal stake into the ground ignited a 2018 blaze in Northern California the killed a firefighter and became the largest in state history.

The California Department of Forestry and Fire Protection said Thursday the blaze started July 17, 2018 in Mendocino County and quickly spread aided by tinder dry vegetation, strong winds and hot temperatures. It spread to Colusa, Glenn and Lake counties.

The blaze burned a total of 640 square miles (1,660 square kilometers), much of it in the Mendocino National Forest, making it the largest in state history. It also destroyed 280 structures and killed a firefighter from Utah.

Cal Fire did not identify the person who ignited the blaze. It says no charges will be filed.