JUST SIX MINUTES after Donald Trump began speaking to a crowd of supporters in Butler County, Pennsylvania, a pop was heard. Mr Trump’s hand immediately went to his right ear. More pops followed. Mr Trump ducked; his Secret Service protective detail jumped on top of him. The crowd began to scream. One minute later, his agents and police began shouting “shooter’s down” and “we’re clear” to one another. They lifted Mr Trump up, surrounding him. He paused, then raised his fist defiantly into the air several times before his bodyguards rushed him out.