A bystander who was seriously injured when a Minneapolis police officer tossed a flash-bang grenade into his vehicle has sued the department, saying police never should have resorted to the tactic.

Jerrod Burt and a friend were sitting in his parked car March 2 in the area of 1100 Van White Memorial Blvd. on the city's Near North Side when the stun device landed inside and detonated against Burt's body as he sat in the driver's seat, leaving him with second- and third-degree burns to his right arm and chest, the lawsuit alleges.

The suit, filed in federal court Thursday, seeks $6 million in damages.

"He was treated like crap and let me put it this way: This would not have happened in a different area of Minneapolis," said Steve Meshbesher, one of Burt's two attorneys.

The suit says that Burt's friend, Leonard Sampson, who was in the passenger seat, was being sought by police for "nonviolent" drug charges, but a search warrant filed in the case didn't mention Burt or his vehicle, nor authorize "the unannounced entry of any other residence or vehicle." Further, police didn't find anything illegal inside the vehicle, the suit says.

"While being initially treated at the back of an ambulance on scene, Mr. Burt asked one of the officers what was going on. In response, the officer informed Mr. Burt that the incident had nothing to do with him," the lawsuit read. "At the time Defendant John Doe deployed the grenade into Mr. Burt's vehicle, neither he nor any other law enforcement officers had reason to believe Mr. Sampson or Mr. Burt would react violently to law enforcement's execution of the warrant. No reasonable officer would have believed Mr. Sampson or Mr. Burt would have acted in a violent manner."

The Office of Police Conduct Review, which investigates complaints of misconduct against Minneapolis officers, has opened an inquiry into the March 2 incident, and a supervisor in the case has since been reassigned. Sgt. John Biederman, a decorated veteran detective, was reassigned from the weapons unit to the robbery unit in April, according to department records. Police spokesman John Elder said that the department routinely transfers officers between units for a variety of reasons, and that there was no indication that Biederman was reassigned because of the incident.

"I'm unaware of him being moved due to performance and I'm usually made aware of that stuff," said Elder.

A popular but controversial tactic used by SWAT teams, flash bangs emit deafening booms and bright flashes meant to momentarily disorient suspects and give officers key seconds to make tactical moves. But the devices, also known as concussion or stun grenades, have fallen out of favor with some departments in recent years after a series of costly settlements over incidents of fires, injuries and even deaths.

In 2011, Minneapolis officials approved a $1 million settlement after a botched drug raid the year before in which an officer threw a flash-bang grenade into a south Minneapolis apartment, burning the flesh off a woman's leg. Meshbesher said that he hasn't yet been able to establish who threw the flash-bang grenade because the department has been slow to turn over police reports.

"This is not the way things should be, and whatever gloves some lawyers use are off," Meshbesher said. "The gloves, I've taken them off — I'm not going to be nice about it."