(REUTERS) - The Tulsa County Sheriff's office released video recently showing the accidental shooting by a police officer of a man he was trying to arrest after mistaking his service weapon for a stun gun in early April.

Eric Harris, in his 40s, was shot by a reserve deputy on Thursday (April 2) following a foot chase, according to the sheriff's office.

The video shows Harris entering a car to sell ammunition and a semi-automatic pistol to an undercover police officer.

When backup officers arrive to make an arrest Harris fled, and when police caught up with him, he resisted arrest according to police.

Reserve Deputy Robert Bates, a 73-year-old former police officer, was trying to help officers take Harris into custody when he fired his gun, the statement said.

"Initial reports have determined that the reserve deputy was attempting to use less lethal force, believing he was utilizing a Taser, when he inadvertently discharged his service weapon, firing one round which struck Harris," police said.

The sheriff's office said Harris continued to struggle after the gun was fired, and might have been under the influence of drugs. He was described as a felon and had been under investigation for narcotic sales.