June 6 (UPI) -- California fire officials revealed Thursday that a hammer sparked the largest wildfire in the state's history last summer
A California Department of Forestry and Fire Protection incident report said the Ranch Fire, which consumed more than 400,000 acres began as a small fire that was caused by a spark or hot metal fragment landing in flammable material.
"The spark or hot metal fragment came from a hammer driving a 24-inch metal concrete stake into the ground," the report stated.
The small fire became a part of the Mendocino Complex when it joined with the River Fire, which started an hour later.
Cal Fire Mendocino Unit Chief George Gonzalez received a verbal statement from a property owner, whose identity was redacted from the report, saying he was responsible for the fire by hammering the stake into the ground.
No charges were filed against the man.
The Ranch Fire consumed 410,203 acres and burned for more than a month after starting on July 27.
It destroyed 157 residences and 123 other structures and was responsible for three injuries and one fatality, according to Cal Fire.