A Donald Trump supporter told the BBC how he tried to alert the Secret Service about the man who fired at the former president.

The eyewitness revealed what he had seen during an extraordinary interview broadcast live on TV.

The man, known only as Greg, said he saw the man – who has been named as 20-year-old Matthew Crooks “bear crawling” on the roof of a building while carrying a rifle.

However, he said the Secret Service failed to respond to his warnings in time to prevent the gunman from opening fire.

The former president was shot at as he addressed a rally in Butler, Pennsylvania.

“I was shot with a bullet that pierced the upper part of my right ear,” Trump posted on his social media site, Truth Social, after receiving hospital treatment.

Wearing a red ‘Trump 2024’ visor, the eyewitness told the BBC’s Gary O’Donoghue: “We all decided, when we hear Trump up there we’re going to walk up through the field, stand by the trees up there in the shade and listen to the rally,” he said.

“We couldn’t see him, but we could hear him. So we walked up and probably [after] five to seven minutes of Trump speaking, we noticed a guy bear crawling up the roof of the building beside us, 50 feet away from us.

“We’re pointing at the guy crawling up the roof. We could clearly see him with a rifle, absolutely. 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 didn’t know what was going on. We’re saying ‘right here on the roof, we can see him from right here, he’s crawling’.

“I’m thinking to myself ‘why is Trump still speaking, why have they not pulled him off the stage?’. I’m standing there pointing at him for two or three minutes. The Secret Service is looking at us from the top of the barn. I’m pointing at that roof, and next thing you know five shots rang out.”

He said the Secret Service officers “probably” could not see the gunman from where they were, but he added: “Why isn’t there Secret Service on all these roofs here? This is not a big place.”

Asked by O’Donoghue what happened next, Greg said: “They blew his head off. Secret Service blew his head off.

“They crawled up on the roof, they pointed their guns at him, they made sure he was dead, and that was it, it was over.”

Prime minister Keir Starmer has said he is “appalled” by the incident, while US president Joe Biden described the attack as “sick”.