Once the police start shooting, how many shots they fire is insignificant. Don’t bring a knife to a gun fight. There is a video on the web somewhere of a similar situation in South America. The cops were too hesitant to shoot and the bad guy managed to cut one or two and actually killed one. Remember the 21 foot rule. A person can cover 21 feet before even an experienced person can draw a gun.
They had their guns out and aimed at him.
Why didn’t they release the dog?
The potential distance an average man can travel and function after receiving a fatal wound is 210 feet/ 70 yards in 14 seconds.
The officers had no choice but to shoot. Letting the knife man walk away is not an option and there is no nonlethal force options.