The Secret Service had detected days before that the gunman shot Trump from a building and “someone should have been on the roof”

The roof from which 20-year-old gunman Thomas Matthew Crooks shot Donald Trump had been flagged as a potential security concern by the Secret Service before the assassination attempt, NBC News reported.

The offenders climbed onto the roof of a building belonging to a glass research company that was 150 yards from where Trump was speaking on a stage in Butler, Pennsylvania. A source told NBC News:

“Someone should have been on the roof or securing the building so that no one could get on the roof.”

The Secret Service had indicated that the building should be under the jurisdiction of local police because it was outside the perimeter of the demonstration, according to the report.