The utility company that provides much of California with natural gas and electricity told state regulators Friday that it plans to cooperate with any investigations into the cause of a massive wildfire in the northern part of the state that has killed at least nine people.

That assurance from officials with Pacific Gas & Electric Co. (PG&E) came after the company said it experienced a problem with one of its major electrical transmission lines at a remote site in Northern California early Thursday, just a few minutes before reports of the so-called Camp Fire, which has caused almost total destruction in Paradise, a town of about 26,000 people in Butte County, company officials and media reports said.

PG&E said it has notified the California Public Utilities Commission about the equipment problem, San Francisco's KQED-TV reported.

PG&E's 115-kilovolt Caribou-Palermo line experienced a power outage in Butte County at 6:15 a.m. Thursday, according to the company, while Cal Fire (California Department of Forestry and Fire Protection) said the blaze began at 6:29 a.m., according to the KQED report.

The utility said it later observed damage to a transmission tower on the line near Paradise, about 180 miles northeast of San Francisco.

Since the fire ignited, at least nine people have been confirmed dead, nearly 6,500 homes and 90,000 acres have burned and about 30,000 residents have evacuated, media reports said.

Lynsey Paulo, PG&E spokeswoman, said Friday that the information about the power line was preliminary and stressed that the cause of the fire remained under investigation.

Meanwhile, PG&E's shares plunged more than 16 percent Friday -- the biggest one-day drop for the utility's stock price since August 2002, CNBC reported. The utility has a history of sparking wildfires -- including some that result in fatalities -- because of faulty equipment, the report said.

The Associated Press contributed to this report.