 The Butler County Sheriff says his department, which was on scene, was not responsible for sweeping the roof where the shooter was perched. The Sheriff's Office was not asked to do that, and I don't know whose responsibility that would have been. Sources tell CBS News that the Secret Service didn't clear it either, since it was outside the secure perimeter. But a source with direct knowledge of the incident says three snipers from local law enforcement were staged within the building just beneath the shooter. We'll