Need more details...
Were the officers IN the car that backed into?
Was the backing up a traffic maneuver or an aggressive act of assault against an occupied vehicle?
That should do it...
I don't think it necessarily matters.If anyone,police or civilian,was in *or* near the cop car then a reasonable fear of serious injury/death exists.The nature of the backing up maneuver would be noteworthy if it was type of thing you or I would do trying to get out of a parking space,however.That's why I suggested earlier that it would be helpful if the incident was caught on a police dash cam.