Mr. Newsom said Monday that he had been “in constant contact throughout the week and over the weekend” with the company and regulators. “Everyone’s immediate focus is, rightfully, on ensuring Californians have continuous, reliable and safe electric and gas service,” he said.

Fire investigators determined PG&E to be the cause of at least 17 of 21 major Northern California fires in 2017. It is also suspected in some of the 2018 wildfires that have been described as the worst in state history, including one that killed at least 86 people and destroyed the town of Paradise.

PG&E said it faced an estimated $30 billion liability for damages from the two years of wildfires, a sum that would exceed its insurance and assets. The bankruptcy announcement, in a filing with federal regulators, led the company’s shares to plunge more than 50 percent.

The shares had already lost almost two-thirds of their value since a wave of wildfires in early November, and its bond rating had been downgraded to junk status by two rating agencies.

California’s utilities have been seeking favorable regulatory and legislative support to guard themselves against wildfire liability — but none more than PG&E, the primary gas and electricity supplier to the northern half of California, serving about 16 million customers over 70,000 square miles.