A policeman is there to keep us safe from people like the guy with the knife . and all others that would do us harm. If a criminal is killed , and I'm NOT saying this guy was a criminal , society is better off with that person gone vs a policeman who's ability to help others is ended. The criminal will never harm anyone again.  People choose their path in life .  The up side of gang shootings , is more criminals are removed from society . As long as no innocent people are hurt in the cross-fire it's a win, win situation .   In Furguson is was sad that one group of people sided with the thug despite all the evidence showing he was charging the policeman.  Do you have a problem with the Black Lives Matter group that they protest anyone who say's all lives matter ?  People have the potential to do good or bad , but they usually make that choice by around 18 years old.   Thanks for asking.