Ventura County, CA, officials said Wednesday a lengthy investigation has determined windy conditions caused two Southern California Edison Co. (SCE) transmission power lines to collide and start the Thomas Fire in 2017, which burned for 40 days, killed two people and destroyed more than 1,000 structures.

Erupting in early December 2017, the Thomas Fire scorched 281,893 acres, consumed 1,063 structures and resisted 100% control until Jan. 12, 2018.

The Ventura County Fire Department (VCFD) determined high winds caused SCE power lines to come into contact in a “line slap,” creating an electrical arc that spilled hot burning materials onto the ground. The report called the ground “a receptive fuel bed that caused the fire.”

With SCE senior executives raising concerns about fires last year, they took exception to the VCFD report, but said the utility cooperated fully with the investigation. The utility said an internal investigation showed the fire was actually two fires with separate causes. SCE said it calculated an earlier start time for at least one of the blazes before utility equipment was shown to be involved.

According to the utility, one fire began in Anlauf Canyon and the other near Koenigstein Road in the city of Santa Paula, and “based on currently available information, SCE has not determined whether its equipment caused the ignition in the Anlauf area.” SCE said the VCFD report does not recognize any of the company’s findings.

The Edison International utility said it has evidence that the ignition of the Anlauf Canyon fire started at least 12 minutes prior to any issue involving the SCE system, and at least 15 minutes before the start time identified by VCFD’s report. “SCE provided this evidence to the California Department of Forestry and Fire Protection (CAL FIRE),” the company said, adding that VCFD investigators didn’t indicate the evidence was considered. “SCE obtained publicly available radar data showing a smoke plume in the Anlauf Canyon area emerging well in advance of the report’s indicated start time.”

Ultimately, the Thomas Fire threatened four cities and rural areas in the county, including Ventura, before it spread into neighboring Santa Barbara County. At one point, nearly 9,000 emergency personnel from across the western United States were deployed.

Besides VCFD personnel, the investigative team working on the origin and cause of the Fire included CAL FIRE, the Ventura County Sheriff’s Office, the Santa Barbara County Fire Department and the U.S. Forest Service.

Meanwhile, regarding other 2017 fires that ravaged Northern California, prosecutors in four counties on Wednesday decided that there will be no criminal charges brought against Pacific Gas and Electric Co. (PG&E), the San Francisco-based combination utility that is now in Chapter 11 bankruptcy reorganization because it faces an estimated $30 billion in liabilities from nearly 20 fires from the past two years.

Prosecutors in Sonoma, Napa, Humboldt and Lake counties said they will not file any criminal charges against PG&E, which currently is serving five years of probation with a federal district court in San Francisco for its guilty verdicts on five of 11 counts of violating natural gas pipeline safety regulations related to the September 2010 San Bruno gas transmission pipeline explosion that killed eight people.

In a statement regarding the 2017 wine country fires, the Sonoma County district attorney said there is insufficient evidence to prove that the utility acted “with reckless disregard for human life” in contributing to the cause of the fires.