Most incidences of gun violence end with the shooters dead on the scene. With the Tsarnaevs it was questionable whether they would ever be found. We don't need to conjecture about what would happen if a "terrorist" was on the loose with guns--it happened 2 months ago. His name was Christopher Dorner (http://en.wikipedia.org/wiki/Christopher_Dorner) and they assembled multi-agency taskforces and set off on a manhunt equally resource intensity as the hunt for the Tsarnaevs.