Officials said the car, a silver Chevrolet Cruze, matched the description of one involved in the [13 minutes] earlier shooting and appeared to have gunfire damage to its back window . . . Officers found two firearms on the floor of the car.
The police had grounds for a reasonable belief that this was the car from which shots were fired - vehicle description (although I'm not sure how detailed that was) plus indications of possible gunfire damage to the car. After the fact, we have further indications that they were correct, although ballistics tests will give a final answer. Given the information the police officer had at the time, shooting a fleeing suspect was both reasonable and legal. I don't always approve of police shootings, but I do approve of shooting a "fleeing felon" when there is a reasonable belief that the running suspect poses a danger to the community. In this case, that belief was reasonable.
My understanding is the car already had bullet holes in it (from the previous shooting) - in terms of the vehicle description.