Donald Trump attack eyewitnesses share horror: 'They blew shooter's head off'

Donald Trump assassination attempt: The attacker reportedly shot at the rally from the roof of a building linked to AGR International, a manufacturing plant.

Donald Trump survived an assassination attempt on Saturday at his Pennsylvania rally, days before he was to accept the Republican nomination for a third time. A barrage of gunfire ended after the deaths of a spectator and the shooter, and serious injuries to two rallygoers. The shooter, who wasn't an attendee of the rally, had attempted to eliminate the business tycoon-turned-politician from an elevated position, before being killed by the United States Secret Service sleuths in retaliatory fire. The law enforcement agencies later recovered an AR-style rifle at the scene.

Republican presidential candidate former President Donald Trump is surrounded by U.S. Secret Service agents as he is helped off the stage at a campaign rally in Butler.(AP)

The attacker reportedly shot at the rally from the roof of a building linked to AGR International, a manufacturing plant. The roof was less than 150 meters from the dais. Eyewitnesses said the shooting triggered panic and a state of utter confusion at the rally venue.

“Everybody went to their knees or their prone position, because we all knew, everyone becoming aware of the fact this was gunfire,” said Dave McCormick, the Republican candidate for U.S. Senate in Pennsylvania, who was sitting to Trump's right on stage.

He said he later noticed that someone had been hit by the bullet behind the stage.

A man named Joseph told NBC news that a man beside him was hit on the head by a bullet.

"I heard several gunshots. The man beside me suffered a gunshot to the head, was instantly killed (and) fell to the bottom of the bleachers. Another woman looked like she got hit in the forearm or hand," he said.

The victim, apparently, was in the way between the gunman and the president, he added.

An eyewitness told the BBC he saw the shooter climb on the roof of a low-rise building just outside the security perimeter with a rifle. He shouted to nearby police officers to alert them to the potential threat.

"Secret Service blew his head off. They crawled up on the roof, they had their guns pointed at him, made sure he was dead, he was dead, and that was it, it was over," he added.

Rico Elmore, the vice chairman of the Beaver County Republican Party who was sitting in a section for special guests, facing Trump, described the incident as "horror".

As the first shot was fired, Donald Trump clutched his right ear with his right hand. Later he pumped his fist in the air in a show of strength as the agents scrambled to shield him. He was whisked away from the crime scene to an SUV.

He later said a bullet pierced through his right ear.

With inputs from AFP, AP, Reuters