We don't have context, so a lot of people are just guessing. My own interpretation is that the driver was identified as a rioter. The police were in a hurry or felt threatened, or were otherwise unable just then to take him into custody. However, they rapidly responded to his being in possession of a deadly weapon (which a car is), and they peacefully neutralized it.

It seems harsh, but rioters do not have the privilege of driving cars, and that's the way it should be.