WATCH: Body camera captures Oklahoma cop fatally shooting man outside church wedding

An officer was involved in a fatal shooting for the first time since police in Muskogee, Oklahoma began wearing body cameras, the Tulsa Worldreports.

In the video, Officer Chansey McMillin -- who was responding to call that a man outside the Old Agency Baptist Church was telling people his ex-girlfriend "had a bullet with her name on it" -- approaches 21-year-old Terence Walker and tells him he is going to pat him down for weapons.

"Just relax for me," McMillin says as he pats Walker down. "What are you shaking for?"

At that point, Walker takes off running with McMillin in pursuit. After a few seconds, Walker bends down to pick an item he dropped and briefly turns toward McMillin with the item pointing towards him.

Officer McMillin fires six shots at Walker, striking him three times.

The pastor from a nearby church who initially called the police then rushes up to Walker's body, which had half-fallen into the ditch. "I'm the pastor, let me check on him" he tells McMillin, who yells at him to "Get back! Get back! Sir, get back, he has a gun!"

Other police are on the scene within minutes. "I was in a bad spot," McMillin tells them.

As they search Walker's body, police find what they claim to be a loaded handgun on it. A few minutes later, the pastor who had implored Officer McMillin to allow him to render Walker aid can be heard telling other officers on the scene that Walker "resisted him."

McMillin, the pastor says, "did everything by procedure. [Walker] resisted him, he resisted him. I'm the pastor who called it in. He asked him," the pastor says, pointing at Officer McMillin, "'do you have a weapon on you?' then he jumped off him and jumped off running."

After hearing that, McMillin leans against his car and asks, "Why did [Walker] have to do that?"

Officer McMillin has been placed on mandatory administrative leave after the shooting, as this was the second one he has been involved with in the last six months. In July, he shot -- but did not kill -- Angel Cerda, who had allegedly attacked a man with a knife and was advancing toward McMillin with a knife raised.

McMillin was praised by Police Chief Rex Eskridge for his use of non-lethal force in that shooting.

Watch the entire 9-minute-long video of the incident and its aftermath below.