On Sunday evening, firefighters were battling more than a dozen fires across Northern California, including a new one called the Jerusalem fire that was exploding north of Napa in Lake County.
Then they received reports of another fire nearby. Officials quickly determined this fire had been set intentionally by a man allegedly trying to protect his marijuana-growing operation.
Juan Ramos Silva, 49, of Lower Lake was taken into custody on suspicion of arson and setting a backfire, according to the California Department of Forestry and Fire Protection.
Silva started the large backfire at 5:43 p.m. Sunday, a couple of miles away from the Jerusalem fire in a rural, sparse area northeast of Middletown, said Lt. Steve Brooks of the Lake County Sheriff's Office.
Silva told deputies he started the blaze to prevent the Jerusalem fire from reaching his home. But officials concluded he set the fire behind the marijuana grow to "protect his plants, not his residence," Brooks said.
Silva told deputies he was a firefighter in Mexico years ago and "had attempted to conduct a controlled burn on the back of his property to protect it."
As some firefighters dealt with that blaze, a much larger force was evacuating residents and trying to control the Jerusalem fire, which burned 5,000 acres in less than a day, fueled by drought conditions and winds.
More than 10,000 firefighters are battling 18 fires in California. More than 50 fire engines from Arizona, Nevada and New Mexico were sent to California to bolster the army.
Silva is the fifth person arrested on suspicion of arson in the last two weeks, according to CalFire.
"Especially now with the dry conditions from the drought, we will absolutely not tolerate arson of any type and will track down those suspected of causing harm to our communities," CalFire Chief Ken Pimlott said in a statement.
CalFire spokeswoman Amy Head said 95% of all fires are started by people.
"If you live in California, you need to be prepared," she said.
Because of the drought, firefighters are experiencing unprecedented fire activity that is aggressive and explosive, Head said. Fires are usually fanned by winds. But that's not the case this year. Bone-dry woodlands are driving flames, and fires are becoming unpredictable.
The Jerusalem fire, she said, is the latest example of how dry brush and rugged terrain could be explosive.
Residents in Lake County are now dealing with two large wildfires consuming thousands of acres of woodlands north of Napa: the Jerusalem fire and the Rocky fire. The causes of the fires are under investigation.
The Jerusalem fire, named for its proximity to Jerusalem Road, came days after firefighters began to gain ground on the massive Rocky fire. The Jerusalem fire started at 3:42 p.m. Sunday, CalFire officials said.
Firefighters battled the blaze as flames moved northeast in dense brush and steep terrain, toward nearby communities. Crews and additional resources were pulled away from the Rocky fire to help several miles south in the firefight.
Residents living in the Jerusalem Valley area east of Spruce Grove Road are under mandatory evacuation orders.
Firefighters were still battling the 69,636-acre Rocky fire, which was 85% contained. The erratic blaze that burned across three counties destroyed 43 homes and 53 outbuildings; eight structures were damaged.
The Rocky fire is the largest burning in California.
Strong winds are expected across northeastern California and parts of the northern Sierra Nevada. Parts of Del Norte, Humboldt, Siskiyou and Trinity counties will be under a red flag warning and fire weather watch starting Monday afternoon because of gusty winds and possible dry lightning.