In this Oct. 14, 2017, file photo, PG&E crews work on restoring power lines in a fire ravaged neighborhood in an aerial view in the aftermath of a wildfire in the North Bay city of Santa Rosa, Calif.

LOS ANGELES — Pacific Gas & Electric Co., California's largest electric utility, warned Friday afternoon it might cut power this weekend to tens of thousands of customers in its service area due to extreme fire risk.

It follows the California Public Utilities Commission last week approving expanded blackouts in high fire-risk areas to reduce wildfire danger. Proactively shutting down power is part of wildfire mitigation plans filed recently by several major utilities.

PG&E filed for bankruptcy protection in late January after being hit with a flood of lawsuits from devastating wildfires in Northern California in recent years.

The utility tweeted Friday afternoon it was "actively monitoring weather conditions" and might cut power "within the next 18 to 36 hours in areas of the North Bay and the Sierra foothills where extreme fire risks exist." Those are some of the same regions that have experienced catastrophic wildfires in recent years.

The National Weather Service issued a red flag warning for Friday evening through Sunday afternoon in portions of Northern California, meaning there is an increased chance of wildfires due to strong winds, low humidity and warm temperatures.

The state is bracing for perhaps another severe wildfire season after catastrophic 2017 and 2018 blazes that killed more than 120 people. California has a history of power lines sometimes sparking wildfires, including during high wind conditions when trees and their branches can knock down lines.

"De-energizing power lines may be necessary as a last resort to avert devastating utility caused wildfires," California Public Utilities Commissioner Clifford Rechtschaffen said last week after the regulator approved wildfire mitigation plans for power companies.

Utilities are responsible for clearing brush and trees from power lines to prevent fires. In California, utilities face liability under what's known as inverse condemnation as well as for negligence claims for wildfire and other damaging incidents caused by such things as power lines or other utility equipment.

According to PG&E's website, its wildfire mitigation plan includes a so-called public safety power shutoff option that could "last several hours or days."

The drastic step of cutting power has raised concern that the elderly, disabled and those with special medical needs could be at risk if outages last an extended amount of time.

"There's a lot of concern that these power shutoffs will be the cause of a lot of endangerment," said Mark Toney, executive director of The Utility Reform Network, a consumer group.

Overall, PG&E has more than 16 million electric and gas customers in its coverage area.

PG&E's has warned a "power outage could impact any of the more than 5 million customers who receive electric service from PG&E. This is because the energy system relies on power lines working together to provide electricity across cities, counties and regions."

Cal Fire blamed the San Francisco-based electric utility's equipment for at least 17 wildfires in the state's wine country in October 2017, including two blazes that resulted in a total of 13 fatalities.