The Holy Fire started Monday in the Cleveland National Forest's Holy Jim Canyon and has so far destroyed a dozen structures, according to fire authorities.
Holy Jim Volunteer Fire Department Chief Mike Milligan, 71, says he's known the arson suspect, Forrest Gordon Clark, for decades and has long warned that he posed a danger to the community.
"I've been trying for years to get someone to pay attention and nobody has really had the opportunity to do that until now," he said.
Milligan said he was so wary of Clark that he avoided altogether going to the area of the remote Orange County canyon where the 51-year-old Clark lives, he said. Nonetheless, Clark came to his home two weeks ago to return items he said he had "borrowed" from the fire department, he said.
"I said 'I want nothing to do with you, Forrest. Just go,'" Milligan said. "He was being gentlemanly in the beginning and turned and then swore at me and turned and left and was quoting the Bible. Later, he came back and told me what a jerk I was and everyone was after him."
The next morning, Milligan said, he got a mysterious text from an unknown number: "911 call sheriff." Milligan called back and though the reception was poor in the canyon, he recognized Clark's voice, he said. Later came another expletive-laden text that ended with the ominous warning: "The place is going to burn just like you planned."
"I had no idea what he meant," Milligan said, adding that Clark sent emails to other people in which he talked about burning something.
"Remember when Gandalf said, 'If there is a dragon in the neighborhood, include it in your plans?'" Milligan asked, paraphrasing the wizard in J.R.R. Tolkien's "The Hobbit."
"He was the dragon."
Clark is being held at the Orange County Jail on $1 million bail and is expected to make a court appearance Friday.
According to a criminal complaint filed Thursday, he is charged with aggravated arson, arson of inhabited property, arson of forest, criminal threats, two counts of resisting and deterring an executive officer and arson burning multiple structures.
The charges being leveled against Clark carry a maximum sentence of life in prison, said Susan Schroeder of the Orange County District Attorney's Office.
"Arson is a terrible crime that destroys dreams," she said in a press conference.
Witness statements, physical evidence and burn patterns connect Clark to the fire, said Shane Sherwood with the Orange County Fire Authority.
Before he was arrested, Clark told a freelance cameraman he was asleep when the fire started and had no idea how it began.
"Who would go out with low humidity and high wind and highest heat temperatures this time of year and intentionally set the forest on fire?" asked Orange County Supervisor Todd Spitzer during Wednesday's press conference.
The Holy Fire continues burning across Orange and Riverside counties, two of the state's most populous, and as of Thursday morning had scorched more than 9,600 acres -- an almost 50% increase from the night before. It remains only 5% contained, according to the national forest's Twitter feed.
"Firefighters continue to battle the blaze around the clock," the national forest tweet said. "We expect favorable weather conditions this weekend to help these efforts."
Schools have been closed in Menifee, Perris and Lake Elsinore.
With temperatures soaring past 100 degrees, an excessive heat warning has been issued for the fire area.
Although it's not the largest fire burning in the state, there are growing concerns about how it could affect residential communities, including Lake Elsinore. Some small communities in Riverside County are under mandatory evacuation orders affecting about 7,000 residential structures, according to authorities.
"We know this district burns, but it should never burn because of an intentional act," Spitzer said. "This shouldn't be called the Holy Jim Fire; this should be called the Holy Hell Fire."
Residents are scared and fleeing their homes, he said.
"They're leaving property behind. They're putting everything they can in the back of their cars as quickly as possible."
Fire officials warned residents to heed evacuation orders.
"Even if you're miles away, you want to be prepared if you're near the fire area or in an environment that can burn," said Thanh Nguyen with the SoCal Team One Fire Management Team, who suggested having a packed bag ready to go.
Firefighters in California are battling 15 large fires.
The second biggest fire is the Carr Fire in Shasta County, also in Northern California. The deadly fire has been burning for more than two weeks and consumed 177,450 acres as of Thursday morning. It has killed eight people, including three firefighters, and destroyed almost 1,100 homes.
The third largest is the Ferguson Fire, near Yosemite National Park, incinerating more than 95,000 acres. The fire has lasted more than three weeks and killed two people.
CNN's Cheri Mossburg, Joe Sutton and Dave Alsup contributed to this report.