Five firefighters were injured in northern California's Rices fire.
The CAL FIRE Nevada Yuba Placer Unit said that the Nevada County blaze had spread over 904 acres of brush and woodland.
It was 10% contained on Wednesday, with steep access making it difficult.
As the Grass Valley Air Attack Base dropped more than 80,000 gallons of fire retardant that day alone, power outages were reported in the area and there was damage to transmission lines.
CAL FIRE said that roads were closed and the Nevada County Sheriff wrote that all evacuation orders and warnings are still in effect.
"Working with CAL FIRE and Pacific Gas and Electric Company, we will begin repopulation only once it is safe to do so. As more information on possible timelines is known, we will share it here and with our media partners," the office said.
CAL FIRE said the fire posed a threat to critical infrastructure, structures, endangered species, watersheds, and cultural and heritage resources.
The Sierra Nevada wildfire has destroyed a building and was a threat to more than 250 homes, authorities said Wednesday.
The condition of the injured firefighters was unknown.
The fire started Tuesday afternoon – its cause is under investigation – and the California communities of Birchville, Sweetland, French Corral, Bridgeport, Rices Crossin and the Buttermilk area were under evacuation orders.
According to FOX Weather, water and fire retardant dropping planes and helicopters were grounded until 11 a.m. local time on Wednesday due to low visibility created by fog.
It said more than 370 firefighters are working to fight the fire.
More than 4,500 wildland firefighters and support personnel are assigned to incidents across the U.S.
The Associated Press contributed to this report.