A man with a rifle could be seen on a rooftop minutes before shots were fired at a Donald Trump rally in Pennsylvania, a witness has told the BBC.

Greg, the witness, said the man was armed with a rifle and had crawled on top of a building just outside the event in Butler County on Friday evening.

He said he pointed the gunman out to police.

“I’m thinking to myself ‘Why is Trump still speaking, why have they not pulled him off the stage’… the next thing you know, five shots ring out,” he told the BBC.

The former president was swarmed by Secret Service agents and escorted away. He could be seen with blood on his ear after the shots were heard.

Greg, who was listening to the rally from outside the event said he saw the gunman around five minutes into Mr Trump’s speech.

“We noticed the guy bear-crawling up the roof of the building beside us, 50ft away from us,” he said.

“He had a rifle, we could clearly see a rifle.

“We’re pointing at him, the police are down there running around on the ground, we’re like ‘Hey man, there’s a guy on the roof with a rifle’… and the police did not know what was going on.”