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The Nuns Fire burns in Santa Rosa, California, Oct. 14, 2017. Getty Images

Tens of thousands of firefighters in California are still working to put out some 15 major wildfires spread across the state. Cal Fire said Sunday “good progress” had been made toward containing those fires, though some 217,566 acres of land have already been destroyed. Forty people have been killed and an estimated 5,700 structures were destroyed so far.

Decreased winds in Northern California allowed firefighters to make progress in pushing back the flames. Some evacuation orders were able to be lifted Sunday morning thank to the containment of some of the fires, Cal Fire announced. Nearly 75,000 people, were still evacuated Sunday morning, down from 100,000.

“We are not out of the woods yet,” Gov. Jerry Brown said over the weekend. “There’s still fires burning.”

Two of the three most destructive fires were more than half contained by Monday, according to CNBC. In Napa and Solano counties, the 50,000 acre Atlas Fire was about 65 percent contained as of Sunday, WITI-TV reported. In Sonoma County, the 48,000-acre Nuns Fire was 40 percent contained, while the 45,000 acre Tubbs Fire was 60 percent contained.

“We’re turning the corner,” said deputy chief of Cal Fire Bret Gouvea. “You’re seeing containment levels coming up. Things feel good in our gut as firefighters. So we just need weather to cooperate with us a little bit.”

Gouvea cautioned against being overly optimistic as some of the fires continued to rage. Even as progress is made toward containment, residents will have to deal with potentially toxic ash and debris left behind by the fires.

“The ash and debris is very toxic,” Karen Relucio, public health officer in Napa County, told WITI-TV. “We strongly urge you not to remove any large debris because this can release toxins into the air.”

As some of the fires died down, authorities and residents began to survey just how extensive the damage to many areas was. Officials warned the death toll could rise as they were able to enter previously inaccessible areas. Hundreds remain unaccounted for, though it was unclear whether they had been unable to check in with family or if they were in danger.

“A week ago this started as a nightmare,” Napa County Supervisor Belia Ramos said Sunday, according to CBS News. “And the day we dreamed of has arrived.”