A witness has narrated how a man with a rifle was seen on a rooftop minutes before shots were fired at former President of the United States of America, Donald Trump. As DAILY POST earlier reported, there was an assassination attempt on Trump during his election campaign rally in Butler, Pennsylvania on Saturday. Greg Smith, who was listening to Trump from outside the event, said the man had crawled on top of a building about 50ft away from the rally. Smith said on sighting the man, he drew the attention of the police by pointing the guman to them. The shooter, who has been identified as a 20-…