(CNN)A Tulsa County reserve deputy is on administrative leave after "inadvertently" shooting a suspect with his gun. Police say Robert (Bob) Bates, 73,  thought he pulled out his Taser during an arrest, but instead shot the suspect, who later died at a local hospital. The shooting happened after an apparent drug and gun selling operation by the Tulsa Violent Crimes task force  Thursday. Bates, a member of the task force, was part of a group of deputies trying to arrest Eric Courtney Harris, 44, in the parking lot of a Dollar General store. Police say Harris, a convicted felon, sold undercover officers a pistol. When confronted by an arrest team, he fled the scene on foot and police say they "observed him reaching for his waistband area ...causing concern for the deputies safety." After a brief pursuit, police say Harris was forced to the ground, where he continued to resist arrest and "refused to pull his left arm from underneath his body where his hand was near his waistband." It was during this portion of the arrest that police say "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." Harris died at a local hospital and his cause of death is under investigation. Police say Harris admitted to medics at the scene that he may have been under the influence of Phencyclidine, a street drug commonly known as PCP. When asked if another gun was found on Harris, Shannon Clark of the Tulsa County Sheriff's Office says "The suspect was placed in the ambulance and transported so quickly. I have not been told there was a second weapon found on him yet." Deputy Robert Bates, who's been placed on administrative leave during the investigation, received his reserve status from the Tulsa County Sheriff's Office in 2008 and was assigned to the violent crime task force. He had also served as a Tulsa Police officer. When asked by CNN affiliate KTUL whether age may have played a factor in the "inadvertent" shooting, Clark says "did an accident happen? Sure. But is it accredited to his age? Or was it accredited to the rapidly evolving situation? I guess that will be determined in the investigation." CNN's AnneClaire Stapleton, Joe Sutton contributed to this report .
Police say Robert Bates, 73,  thought he pulled out his Taser during an arrest .
Instead, he shot the suspect, who later died at a local hospital .