 Authorities believe this was a lone wolf attack. What is not certain, how did this suspect with a gun get on a roof and take a shot at former president of the United States? Already someone under heavy protection. On top of that, witnesses say that they saw the suspect on the roof with a gun and told authorities. Still, the former president gave his speech and was allowed to go forward with the event on stage. Pennsylvania State Police pressed on reports of people warning police before the shooting. Watch.