Man arrested in Petaluma with multiple guns, including possible DIY assault weapon

Petaluma police said they arrested a man on Wednesday in who was allegedly found to have an assault-style gun, multiple other weapons and several loaded, high-capacity magazines in his vehicle.

The man, 18-year-old Christopher Middleton, was said to have a loaded assault rifle equipped with a 30-round magazine, three additional 30-round magazines including one partially loaded, an unloaded shotgun, an unloaded rifle and approximately 500 rounds of ammunition in the vehicle, according to an announcement by the Petaluma Police Department.

Police also said they found a gas mask, knit ski mask, a “military-type” backpack and canteens in the vehicle.

Police arrested Middleton at the Rocky Dog Park on West Casa Grande Road without incident after a caller reported that the suspect had threatened him with a gun during an argument while the two were driving on Highway 101. The two were said to ultimately end up at the dog park, where the victim left Middleton and reported the incident to police.

Officers arrived at the park with guns drawn and set up a perimeter around the area, according to police. Middleton was said to be parked in the south part of the parking lot and was standing next to his car, where police said he was arrested around 4:40 p.m.

Middleton reportedly did not have the assault weapon on him when police arrived, but told police he had been pointing it at trees shortly before his arrest.

Middleton has no known connections to any hate or terror groups, said Petaluma Police Sgt. Paul Gilman. Middleton was described as a transient with no known address, though Gilman said police are looking into connections to addresses, including in the Forestville area.

A search of the car turned up suspected bomb-making materials, prompting a call to the Sonoma County Sheriff’s Office bomb squad, police said. Using a robot, Sheriff’s Office personnel determined that they were fireworks.

Gilman said they did not currently suspect Middleton was planning to use the weapons. Police currently suspect at least some were obtained illegally, and Gilman noted that 30-round magazines like those Middleton reportedly possessed are illegal in California.

Police are still investigating the exact nature of the weapons, including how Middleton came to possess them.

Middleton was arrested and booked at Sonoma County Jail on $10,000 bail for unlawful possession of an assault weapon, unlawful possession of high-capacity magazines, displaying a firearm in a threatening manner and possession of a loaded firearm in a public place.

(Contact Eric Gneckow at eric.gneckow@arguscourier.com. On Twitter @Eric_Reports.)