If you are talking consequentialism then taking one life to save many lives is justified. The person who refused to surrender was one life who threatened many lives. This person showed a willingness to take many lives and wasn't willing to surrender. While it might be better to bring him in alive it may not have been an option.

As far as whether they police used a drone, a gun, or whatever else, it's just a matter of which is the most effective tool to solve the problem while minimizing loss of life. The only thing better than taking one life to save many is taking zero lives to save many.