Dramatic video captured the chaos as rally-goers spotted the gunman on a roof, moments before he opened fire at former President Donald Trump.

‘He’s got a gun!” one person is heard yelling, as another cries out “He’s on top of the roof!’

The gunman, who was then killed by Secret Service snipers, is believed to have crawled on the roof of a building about 130 yards from where the former President was speaking at the Butler Farm Show grounds.