It appears we now know the cause of the largest wildfire in California history.

The Ranch Fire burned through Mendocino, Lake, Colusa, and Glenn counties in the summer of 2018. The blaze left one firefighter dead, destroyed 280 structures and burned more than 410,000 acres.

Now, California Department of Forestry and Fire Protection says it believes the Ranch Fire was caused by a spark or hot metal fragment from a hammer driving a metal stake into the ground. Cal Fire says no charges have been filed in connection to the fire.