To understand how you create perception look back at the airplane picture on the ecsys website. Now let's substitute today's events to make things more clear. When you have all of the props (the school, ambulances, police, SWAT team, a story about a shooter) and actors (grieving parents, grieving teachers, news media, other students) you don't actually need any harmed children. That part of the story is like the airplane. You will never see any real evidence that any children were actually harmed, because they were not harmed, it's not necessary because the other relationships tell you it must be real.