How did would-be Trump assassin get to rooftop vantage point unseen

U.S. authorities are investigating how a young gunman managed to get to a rooftop vantage point last Saturday to shoot former president Donald Trump during a political rally when local police were in the warehouse beneath the gunman and just outside.

"There was local police in that building. There was local police in the area that were responsible for the outer perimeter of the building," Secret Service Director