SANTA ROSA, Calif. (AP) — Power lines buffeted by heavy winds ignited at least two small fires the night of Oct. 8 in Northern California neighborhoods, according to investigators.

The findings by the Santa Rosa Fire Department are the first public reports into what caused some of the dozens of blazes that erupted that night and became the deadliest and most destructive wildfires in California history, the Press Democrat said Saturday.

The city’s investigations focused on two lesser-known fires that burned separately from the large blazes that swept across the region, destroying 6,200 homes and claiming 40 lives.

In both cases — a fire that destroyed two homes and another that damaged an outbuilding — investigators ruled that winds caused PG&E power lines to throw sparks.

“It was determined that the fire damage to the site was a direct result of the high winds causing the power lines to arc, starting a fire in the combustible vegetation,” Fire Marshal Scott Moon wrote in his narrative statement about the Brush Creek blaze.

The city reports, completed late last year and early this year, come as parallel investigations by Cal Fire and the state Public Utilities Commission continue into the cause of the devastating fires. Those inquiries, expected to hold the most sway in assigning any responsibility for the fires’ causes, could be months or more away from completion, according to state officials.

PG&E spokeswoman Deanna Contreras declined to comment on the new reports or the mounting number of lawsuits filed by burned-out residents against the utility giant in connection with October’s fires.

“What I can tell you at this point is that there has been no determination on the causes of the fires (under investigation by the state) and we remain focused on doing everything we can to help Sonoma County recover and rebuild,” Contreras told the newspaper last week.

More than 100 lawsuits filed by displaced residents are pending before a San Francisco judge. They claim the utility failed to maintain and repair its power lines and prepare for the kind of high winds that were forecast and arrived that night.

In addition, Sonoma County government officials last week announced their plans to sue PG&E, seeking tens of millions of dollars in damages to compensate for debris removal costs and damaged infrastructure. Napa, Solano, Yuba, Lake and Mendocino counties are expected to join the case, officials said.

Insurance claims from the Northern California fires have grown to $10 billion, with the largest share of losses in Sonoma County, where 5,130 homes burned and 24 people were killed.

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Information from: The Santa Rosa Press Democrat, http://www.pressdemocrat.com