California's largest utility company said on Sunday its chief executive had resigned as the firm faces billions of dollars in potential liabilities tied to the state's deadly and destructive wildfires last year.

Geisha Williams announced her resignation from PG&E amid growing concerns over the company's role in the devastating Camp Fire, which killed at least 86 people and destroyed more than 18,800 homes and buildings.

Williams, who took the helm in 2017, will be replaced temporarily by the company's general counsel, John Simon, until a full-time chief executive is hired.

Simon held several senior roles within the company, including executive vice president of corporate services and senior vice president of human resources.

Firefighter Jose Corona sprays water as flames from the Camp Fire consume a home in Magalia, Calif., Nov. 9, 2018.(Noah Berger/AP) Firefighter Jose Corona sprays water as flames from the Camp Fire consume a home in Magalia, Calif., Nov. 9, 2018.

"While we are making progress as a company in safety and other areas, the board recognizes the tremendous challenges PG&E continues to face," the company said. "We believe John is the right interim leader for the company while we work to identify a new CEO."

FILE - In this Nov. 10, 2018 file photo, with a downed power utility pole in the foreground, Eric England, right, searches through a friend's vehicle after the wildfire burned through Paradise, Calif. California’s largest utility company is getting battered in midday trading on a report that it’s considering bankruptcy protection in the face of potentially crippling liability damages from a spate of recent wildfires. No cause has been determined for the source of California’s “Camp Fire,” but PG&E reported an outage around the time and place the fire was ignited. Another transmission line also malfunctioned a short time later, possibly sparking a second fire. (AP Photo/Noah Berger, File)(The Associated Press) FILE - In this Nov. 10, 2018 file photo, with a downed power utility pole in the foreground, Eric England, right, searches through a friend's vehicle after the wildfire burned through Paradise, Calif. California’s largest utility company is getting battered in midday trading on a report that it’s considering bankruptcy protection in the face of potentially crippling liability damages from a spate of recent wildfires. No cause has been determined for the source of California’s “Camp Fire,” but PG&E reported an outage around the time and place the fire was ignited. Another transmission line also malfunctioned a short time later, possibly sparking a second fire. (AP Photo/Noah Berger, File)

The cause of the fire, which grew to become the deadliest and most destructive in state history, is still under investigation.

PG&E said an employee discovered a damaged power line near the source of the Camp Fire immediately before the massive blaze broke out.

Analysts said PG&E's wildfire liabilities could be as as high as $30 billion, if the company is found responsible.

Ratings agency S&P slashed PG&E's credit rating to junk status earlier this month, citing growing regulatory and financial concerns stemming from the wildfire probe. The ratings agency cut the company's key rate five notches to "B" from "BBB-."

The utility firm's market value tumbled to $9.12 billion over the last few months, compared to $25.32 billion in October.