It is an act by a deranged coward who wanted to kill people. He was using fully automatic weapons that are not legal to own anywhere in the USA. That is not a hunting rifle. Stop blaming the gun, this guy would have killed people with anything. A car, a bomb anything. He was out to kill innocence people. Evil has a way always to murder regardless of the means. Boston bomber used a pressure cooker.
I have no idea how to stop people like him. He had no criminal records.. No neighbors had issues, his brother was speechless as he had no sign.. How can any police protect against such an evil person