You can see two cops coming for the guy with the knife right before he is shot. One has his taser out, and the other his handgun. The taser hits him first, it definitely worked, and then the other cop (who had been on the scene for only 30 seconds) just unloads his whole clip into him.
Cop with the taser had the situation handled. Only time lethal force should be considered is when it's absolutely necessary.
