Notice how frightened those cops were. They were past thinking rationally, and that mentally ill man with a violent history could just as easily had been someone’s grandfather whittling on a stick with a pocket knife. They don’t care who they murder once they are afraid.
The motto of cops today is “Anything I have to do to go home at the end of the day” - including killing people, dogs, old people, women delivering newspapers before dawn, you name it.