“Power lines coming into contact.”

According to investigators, that is what sparked the 2017 Thomas Fire — one of the largest and most catastrophic wildfires in California history.

A “high wind event” ultimately caused the power lines to touch, creating an “electrical arc” or discharge, the investigators said Wednesday in a final report.

“The electrical arc deposited hot, burning or molten material onto the ground, in a receptive fuel bed, causing the fire,” the report said. “The common term for this situation is called ‘line slap,’ and the power line in question is owned by Southern California Edison.”

Edison and its parent company, Edison International, have been named in hundreds of lawsuits alleging negligence and liability in causing the Thomas Fire. Residents have long suspected that its equipment was to blame.

According to the investigation report, Ventura County Fire officials believe the blaze started in two different areas around Santa Paula. More than 280,000 acres went up in flames and over 1,000 structures were destroyed. Two deaths were reported, including a firefighter.

“In total, the Thomas Fire burned for nearly 40 days, threatening the cities of Santa Paula, Ventura, Ojai and Fillmore, as well as many unincorporated communities, before moving into Santa Barbara County,” officials said. “It was declared 100 percent controlled on January 12, 2018.”

Nearly 9,000 emergency personnel worked on the fire —– with firefighters and first responders coming from all over the country to help. Investigators from CAL FIRE, the Ventura County Sheriff’s Office, Santa Barbara County Fire Department and US Forest Service worked together to determine its origin and cause.