In a statement, the California Department of Forestry and Fire Protection said it "has determined that the Camp Fire was caused by electrical transmission lines owned and operated by Pacific Gas and Electricity (PG&E) located in the Pulga area."
PG&E filed for bankruptcy earlier this year because it was likely to face more than $30 billion in potential liability costs stemming from the fire.
"While we have not been able to review CAL FIRE's report, its determination that PG&E transmission lines near the Pulga area ignited the Camp Fire on the morning of November 8, 2018, is consistent with the company's previous statements," PG&E said in a statement Wednesday.
"Our hearts go out to those who have lost so much, and we remain focused on supporting them through the recovery and rebuilding process," the company said.
PG&E shares were down 3.1% to $17.51 in premarket trading. The stock has fallen 24% year-to-date.