Without the exact statements from the witness its speculation on what they are really trying to convey.
Your statement of "It's a perfectly natural conclusion to go from "shots fired at someone" to "someone was shot.". only improves my statement that witness statements need to be supported by other evidence. With what has been released the "shot in the back" statement does not hold up.
I for one am not throwing out anything. I have stated one should wait till the investigation is done. ALL of the evidence needs to be looked at to determine what happened.
So many times some rush to judgement. Some even try to play the race card (white cop / black teenager).
It was a tragic event. Hopefully the investigation will be done that the results are not questioned. But they will be, no matter the outcome.