FORMER US president Donald Trump called for unity and resilience today, hours after surviving an assassination attempt at campaign rally.

Secret Service agents shot dead the gunman, but not before his attack had killed a person attending the event in the Pennsylvania town of Butler.

The roof where the would-be assassin, identified as Thomas Matthew Crooks, lay in wait was less than 164 yards from where Mr Trump was speaking. 

The far-right billionaire said that the upper part of his right ear had been pierced in the shooting. His aides said he was in “great spirits” and doing well.

“I knew immediately that something was wrong in that I heard a whizzing sound, shots, and immediately felt the bullet ripping through the skin,” he wrote on his social media site. “Much bleeding took place.”

In a subsequent post, Mr Trump said that “it was God alone who prevented the unthinkable from happening.

“In this moment, it is more important than ever that we stand united and show our true character as Americans, remaining strong and determined and not allowing evil to win,” his post said.

Though Secret Service agents fatally shot Mr Crooks, questions are already being asked about how the gunman was able to get so close to the former president. 

President Joe Biden was briefed on the attack and spoke to his predecessor several hours after the shooting, the White House said.

“There’s no place in America for this type of violence,” the president said. “It’s sick. It’s sick.”

Mr Crooks has been identified as a registered Republican Party supporter but some Republicans have pointed the finger at Mr Biden and his allies for creating a toxic environment. They referred to a comment the president made to donors on July 8 — that “it’s time to put Trump in the bullseye.”

Mr Trump was fit enough after the shooting to fly to New Jersey on his way to the Republican National Convention, which begins on Monday.

He is assured of being confirmed as the Republican Party’s nominee for the presidential election in November, where he is likely to face Mr Biden.

Condemnation of the attack came from across the globe, with China’s President Xi Jinping extending his sympathies to Mr Trump.