Post and Courier has a copy of the gas station security video in the shootout between officer and mayoral candidate Omar Brown and parole violator Antonio Rivers. It plays out pretty much how the police reporter stated that it did.
It does appear that there was a confrontation inside, though it's hard to tell if words were exchanged. Rivers gets right up to Brown's car with his gun by his side when Omar jumps out and starts shooting. Rivers runs from the scene as Brown lays the five bullets in to his back, but it does look like gunfire's exchanged after Rivers has left camera shot, potentially indicating when Brown was shot.
This morning, Solicitor Scarlett Wilson said that Brown was not at fault in the incident.