ORANGE COUNTY, California (CNN) -- One of the larger fires in Southern California was deliberately started by someone with apparent knowledge of arson, a fire official said Thursday.

Firefighter Luke Perisin sets a backfire Wednesday against the Santiago Fire in Live Oak Canyon, California.

The Santiago Fire in Orange County was started in two places along a little-traveled road, according to Chief Chip Prather of the county's fire authority.

The fire, which has burned more than 25,000 acres, was started in brush just off Santiago Canyon Road, not close to homes. It spread rapidly, indicating the arsonist had some knowledge of winds and other factors.

"It is a confirmed arson. There was evidence found at the scene. That is the purpose of our early declaration of it being an arson-caused fire," Prather said. He would not describe the evidence.  Watch how the evidence points to arson »

Prather said officials originally thought the fire had three points of origin instead of two.

The Santiago Fire's points of origin are considered crime scenes, said Jim Amornino, a spokesman for the Orange County Sheriff's Department.

The reward for information leading to an arrest has increased to $250,000 -- $50,000 each from the governor's office, the U.S. agency of Alcohol, Tobacco, Firearms and Explosives, and the FBI, Prather said. KFI radio has chipped in another $100,000, the sheriff's department said.

The state established a toll-free arson tip line at 800-540-7085. Gov. Arnold Schwarzenegger said anyone convicted of arson would be dealt with harshly.

If a suspect is to be found, "it's going to be by a clue from the public," said county Sheriff Mike Corona.

About 1,100 firefighters were working on controlling the Santiago Fire, which has destroyed at least 22 structures, according to Orange County Fire Battalion Chief Kris Concepcion. The California Department of Forestry and Fire Protection said the fire was only 30 percent contained Thursday morning after being 50 percent contained the day before.  Watch the Santiago flames rage »

The motive of the Santiago Fire's arsonist was a mystery to Concepcion.

"That's the part that I really can't figure out, to tell you the truth," he told CNN. "That individual knew on Sunday when this fire started that we had, really, the perfect storm, if you will. We had the heavy Santa Ana winds, we had the low relative humidities, we had the high temperatures.

"And then for someone to even think about doing something as reprehensible as starting a fire where they knew the fire would grow as rapidly as it would -- traveling about three, 3½ miles in about an hour -- is just really absolutely unconscionable," he said.

The smaller Rosa Fire in Riverside County, 100 percent contained at 411 acres Thursday morning, was also probably arson, state officials said.

Meanwhile, Los Angeles Fire Department investigators are looking into whether a man who was arrested on suspicion of arson in the San Fernando Valley may have had a role in any of the ongoing blazes, an L.A. police spokeswoman said.

Catalino Pineda, 41, was arrested Wednesday, Officer Kate Lopez told CNN. Witnesses told police they saw him lighting a fire on a hillside in the West Hills area of San Fernando -- northwest of Los Angeles -- then walking away, Lopez said.

Pineda was already on probation for "making excessive false emergency reports" to police at the time of the arrest, Lopez said. His bail has been set at $75,000, she said.

The fire he allegedly set was brought under control, but now authorities want to find out if he had any role in the other wildfires.

In San Bernardino County, John Alfred Rund, 48, was arrested Tuesday evening and charged with setting a small fire along a rural roadside near Victorville.

Rund was to be arraigned Thursday morning in Victorville. He was being held in lieu of $750,000 bail.

The county's district attorney's office on Thursday also filed arson charges against Anthony Riperti, 47
What number of structures have been destroyed Which authrorities investigated a man for suspected arson? What destroyed 22 structures? What is the gender of the suspect arrested? What is the number of structures destroyed? What is the size of the santiago fire? What area is the santiago fire In how many places, did the fire started? For how many acres, the fire has grown? Which fire grew to 25,000 acres?
22 Los Angeles Fire Department arson-caused fire," man at least 22 25,000 acres, Live Oak Canyon, California. two burned more than 25,000 The Santiago
question: What number of structures have been destroyed, answer: 22 | question: Which authrorities investigated a man for suspected arson?, answer: Los Angeles Fire Department | question: What destroyed 22 structures?, answer: arson-caused fire," | question: What is the gender of the suspect arrested?, answer: man | question: What is the number of structures destroyed?, answer: at least 22 | question: What is the size of the santiago fire?, answer: 25,000 acres, | question: What area is the santiago fire, answer: Live Oak Canyon, California. | question: In how many places, did the fire started?, answer: two | question: For how many acres, the fire has grown?, answer: burned more than 25,000 | question: Which fire grew to 25,000 acres?, answer: The Santiago