I watched some of the videos of the footage, I think the police officers acted properly and in the best interests of public safety.
Faced with someone who's been on a murderous rampage, with what appear to be explosives taped around them, continuing to put up a fight whilst armed with a large knife - I think the police acted in the way I'd expect them too.
Imagine the backlash against the police, if the officer had faltered at the moment of proof, and the attacker had managed to take someone else's life, or god forbid - if the explosives had been real and gone off.