Public safety

Question 1: If it is true that nothing could have stopped Harless from shooting the teacher and assistant principal, then how would you advise administrators to keep schools safe? Was Harless a criminal or victim of domestic violence and suffering from PTSD? Do you feel justice was served? Explain?
Question 2: Obviously the rules and policies made no difference is this situation. How can school officials prepare instructors and staff for emergency situations such as this one?