The fire on Alexander Mountain was set by a Loveland man posing as a police officer, the Larimer County Sheriff’s Office said Wednesday.

Jason Hobby, 49, was arrested Tuesday afternoon and booked into the Larimer County Jail on charges of arson, menacing, improper use of public authority and false imprisonment, jail records show.

Larimer County Sheriff John Feyen said Hobby previously worked at the Sylvan Dale Guest Ranch at the base of Alexander Mountain.

Hobby posed as a police officer or firefighter and stopped travelers in the area during the fire, pointed guns at them and accused them of trespassing, Feyen said.

Feyen said Hobby drove a red pickup truck that he had modified to look like a fire engine. The truck had emblems that read “Twin Buttes Fire Protection District.”

“Based on our research and investigation, we cannot locate a Twin Buttes firefighter anywhere,” Feyen said. “He had firefighting equipment… He had hose reels, he had catch tanks, it was so hard to see that he was able to get through roadblocks to get to the fire scene.”

Sheriff’s officials determined in early August that the fire, which covered more than 3,500 acres, was human-caused and said they planned to release more information about the suspect and the arrest at a 1 p.m. press conference.

The Alexander Mountain Fire began on Monday, July 29, and raged for more than two weeks on private and national forest lands west of Loveland before emergency crews were able to contain the flames.