A 72-acre fire in the Oroville Wildlife area may have been sparked by a 10-acre fire in the same area three days ago.
Fire investigators are piecing together evidence, including hot temperatures and high winds. They said the first fire could have started the second.
Firefighters worked Monday night to stop the wildfire from getting out of hand. Strong winds caused embers to fly, igniting other areas of dry brush and trees.
"We had so many spot fires," said Battalion Cal Fire Chief Russ Fowler. "I would estimate in the neighborhood of 50."
Fowler said the spread was unpredictable, with fire flaring up in several different areas before eventually coming together as a single inferno.
"It whirled around and created significantly high flame lengths," he said.
It threatened homes and a nearby shooting range off Rabe Road.
"If this range wasn't available to us, we wouldn't have anywhere in this area to go to," said shooter Joseph Patrick.
Fire crews took to the sky and ground to keep the blaze contained within the Oroville Wildlife Area.
"This was our Achilles heel that really created all of our problems once this jackpot of fuels got going," said Fowler.
Fire investigators say the fire started very close to where another wildfire burned near the Feather River three days ago. Crews were able to hold the lines at a nearby levy.
They are still investigating if the earlier fire may have re-ignited, including the possibility that an ember flared up from the ground, or a spark blew down from the tree tops.
"They just blow in the wind like that and they land in grass and ignite," said Fowler.
Hand crews and firefighters are working to keep it from happening again.
"Fire crews are marking this area off making sure all of the hot spots are contained so we don't escape the fire lines," said Fowler.
The cause of the fire remains under investigation. Arson has not been ruled out. No one was hurt, and no structures were damaged.
Even though CAL FIRE - Butte County Fire was short-handed with some crews battling the Bully Fire in Shasta County, they were able to call firefighters from Grass Valley and Marysville to assist them.