FILE - In this Thursday, Dec. 14, 2017, file photo provided by the Santa Barbara County Fire Department, shows flames from a back firing operation underway rise behind a home off Ladera Ln near Bella Vista Drive in Santa Barbara, Calif. An investigation has determined that one of the largest and most destructive fires in California history was sparked by power lines coming into contact during high winds. The Ventura County Fire Department says Wednesday that the contact ignited dry brush on December 4, 2017 and eventually blackened more than 440 square miles (1,139 square kilometers). The Thomas fire destroyed more than a thousand structures in Ventura and Santa Barbara counties and resulted in the deaths of two people. (Mike Eliason/Santa Barbara County Fire Department via AP,File)

LOS ANGELES - One of the largest fires in California history was sparked by Southern California Edison power lines that came into contact during high winds, investigators said Wednesday.

The resulting arc ignited dry brush on Dec. 4, 2017, starting the blaze in Ventura and Santa Barbara counties that resulted in two deaths and blackened more than 440 square miles (1,139 square kilometres), according to the investigation headed by the Ventura County Fire Department.

The arc "deposited hot, burning or molten material onto the ground, in a receptive fuel bed, causing the fire," said a statement accompanying the investigative report.

Southern California Edison didn't immediately return a call seeking comment.

The fire destroyed more than 1,000 structures before it was contained 40 days after it began near the city of Santa Paula. A firefighter and a civilian were killed.

A month after the blaze started, a downpour on the burn scar unleashed a massive debris flow that killed 21 people and destroyed or damaged hundreds of homes in the seaside community of Montecito. Two people have not been found.

The investigation was conducted by fire officials in both counties along with the California Department of Forestry and Fire Protection.

Investigators said the Thomas fire first began as two separate blazes that joined together. They determined the utility was responsible for both ignitions.

Edison previously acknowledged its equipment likely started one of the two fires.

Victims claimed in lawsuits that losses from the blaze and flooding were due to negligence by Edison, which has said it will work with insurance companies to handle the claims. The utility is protected from going bankrupt over the disasters, thanks to a law signed last year that passes excess liability costs on to utility customers.

In Northern California, Pacific Gas & Electric Corp. filed for bankruptcy in the face of billions of dollars in potential liability from huge wildfires in that part of the state over the past two years. A blaze in November killed 85 people and destroyed most of the town of Paradise.

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This story has been corrected to state that 85, not 86, people were killed in the Northern California wildfire.

News from © The Associated Press, 2019