The utility was responsible for several of last year’s wildfires that burned through Northern California’s wine country. In fact, Cal Fire has determined that of the 21 major fires last fall in Northern California, at least 17 were caused by power lines, poles and other equipment owned by Pacific Gas and Electric Company.

This year, the utility said that it would begin pre-emptively turning off the power to some customers to avoid causing wildfires under certain conditions.

Cal Fire, once it determines a cause, can seek compensation for firefighting costs — which in the case of the Camp Fire will be staggering, whoever foots the bill. More than 5,600 firefighters were still on the lines on Wednesday, with 23 helicopters in the air and 630 fire engines were on the ground. The fire has burned 138,000 acres and was 35 percent contained.

Whatever set off the blaze — which was first reported early Thursday, just east of Paradise, a town of about 27,000 people in the Sierra Nevada foothills — strong winds roaring through the dry terrain were the reason it spread so quickly and caused so much devastation.

A changing climate is potentially part of the Camp Fire’s story, in deepening patterns of drought in California. Some researchers said that logging in the burned area after a fire in 2008, which was intended to clear out fuels and make this part of Northern California safer, may have had the opposite result. The logging may have left fast-burning weeds and young trees in the fire’s path.

“When it got to the logged area, it spread very rapidly and people just didn’t have much time to evacuate in Paradise, so this whole notion that logging — so-called hazardous fuels reduction — was going to save the town is a dangerous falsehood,” said Chad Hanson, a fire ecologist at the John Muir Project, an environmental group that has been critical of land-management policies and logging practices on public lands. The speed at which the fire spread has raised concerns about the more than 600 who are missing.