The musician, 39, was arrested on Tuesday in Washington after his car was pulled over for speeding and police discovered a cache of weapons and marijuana in the vehicle, the Associated Press reports.
Popper's black Mercedes SUV was clocked at 111 mph on Interstate highway 90, according to the Washington State Patrol. Popper, a Washington resident, owns the car, but Brian Gourgeois, 34, of Austin, Texas, was at the wheel, trooper Jeff Sevigney said.
Officers searched the car with a police dog and found four rifles, nine handguns and a switchblade knife in hidden compartments, as well as a Taser, night vision goggles and a small amount of marijuana.
Authorities, who seized the vehicle, said it was equipped with flashing emergency headlights, a siren and a public address system.
"Popper indicated to troopers that he had installed these items in his vehicle because (in the event of a natural disaster) he didn't want to be left behind," the Patrol said in a statement, which also said Popper told officers he collected weapons.
Popper and Gourgeois were booked at the Adams County jail and released on their own recognizance. Authorities said they plan to charge both men with possession of a controlled substance and possession of drug paraphernalia, and Gourgeois faces a reckless driving charge.
Popper did not respond to the AP's request for comment.
The rocker, who is scheduled to go on tour later this month with his new band, the John Popper Project, is perhaps as known for his weight struggles as for his music.
In 2003, Popper told PEOPLE he had dropped 180 pounds – from a high of 430 – thanks to gastric bypass surgery in 2000 and plastic surgery in 2001 to get rid of excess skin.
"I have big man boobs," he said. "I got plastic surgery to chop them off. They took six pounds off of my chest. Yeah, I was like the Michelin man deflated."
Washington State Patrol / AP