This is an attempted carjacking that goes badly for the criminal.
The defender (who turns out to be an off-duty cop) gives us an excellent example of what to do when the police show up.
Put your gun down, put your hands up. If you can't do that safely around the criminal who just attacked you, then you shouldn't be near enough to the criminal for him to remain a threat.
If you CHOOSE to stay close to a criminal who remains a threat until the police respond, now you are in a pickle because you need to put down your weapon and put up your hands and you have chosen to remain in a situation where you can't do that safely.
Something to think about.