There are two links and a short video. They didn't "chase him down", they were ahead of him by quite a ways-stopped. The perp caught up to them, veered off and went past the passenger's side of their truck. When he got to the front of the truck he turned, ran across in front of the truck and attacked a guy that was standing near the front corner of the driver's side of the vehicle. The guy backed away and the perp kept coming at him grabbing the gun and punching him. The guy shot him and he continued the attack so he shot again. The two links contain info from the police report and a lot of other info about the whole situation and everyone in it. The perp had a record including possessing a loaded gun in a school, resisting arrest, theft...just read the articles. The video has to be watched carefully several time because the swings off to the side and back a couple of time.
This exact same scenario plays out all the time in the cities. I could post the stories and vids all day...
And anyone who thinks the cops and prosecutor are going engage in some conspiracy to protect these guys because they are white haven't been paying attention for the last 50 years. Show me one time where it's happened in this century. Blacks meanwhile can literally murder someone in front of witnesses and never see a jail cell...