Last week saw a young adult in Trollhättan, Sweden casually carry a sword into Kronan school, and kill two people and seriously wound 2 others. Students in the school at first thought the suspect posed no threat, wearing a Darth-Vader mask and a helmet, sword in hand. Students stood with him to take photos. Yet the suspect quickly turned violent and the alarm was raised. Officers on patrol responded to the scene within 10 minutes, and had to use deadly force to stop the attacker in fear that the...