Former U.S. Donald Trump on Sunday said it was divine intervention that helped him survive an assassination attempt during a campaign rally in Pennsylvania and called on Americans to unite.

The shocking incident has opened a dark new chapter in an already polarized U.S. presidential race.

The 78-year-old former president was hit in the ear at a campaign rally in Butler, Pennsylvania while the shooter and a bystander were killed and two spectators critically injured in the worst act of U.S. political violence in decades.

"In this moment, it is more important than ever that we stand United," Trump said in a statement on his Truth Social network, adding that Americans should not allow "Evil to win."

The Republican added that it was "God alone who prevented the unthinkable from happening" and that he would "FEAR NOT."

The gunman has been identified as 20-year-old Thomas Matthew Crooks of Bethel Park, Pennsylvania, about an hour's drive from the rally site, according to an FBI statement early Sunday.

His motive remains unknown.

U.S. President Joe Biden was getting a fresh briefing later Sunday at the White House on the assassination bid against his rival in November's tense election.

The 81-year-old Democrat has called the attack "sick" and spoke to Trump afterward. He also cut short a weekend at his vacation home and flew back to Washington to deal with the crisis.

World leaders have condemned the attack, with the Kremlin on Sunday morning saying there was no place for violence in politics.

Security questions
In scenes that will haunt an America already traumatized by violence and political upheaval, Trump clutched his ear and fell to the ground after gunshots rang out at the rally on Saturday.

Secret Service agents surrounded him, then bundled the former president off stage, as he raised a fist in defiance, with blood streaked across his ear and face.

Trump said afterward that he was "shot with a bullet that pierced the upper part of my right ear" and heard a "whizzing sound."

The shooter, reportedly a registered Republican, was believed to be working alone.

A video published by US outlet TMZ shows the alleged assailant lying on his belly on a sloping rooftop and aiming a rifle. A quick succession of gunshots is heard followed by screams from off-camera Trump supporters attending the rally.

The shocking incident inevitably raised questions about security, and how a presidential candidate could be targeted by a gunman around 150 meters away despite a huge Secret Service detail.

U.S. Secret Service spokesman Anthony Guglielmi rejected "absolutely false" claims that it had refused additional protection for Trump ahead of the rally, saying that the agency had in fact recently added resources for him.

The FBI said in a news conference early Sunday that it was "surprising" the gunman had been able to get off so many shots before he was spotted and "neutralized" by countersnipers.

After multiple witnesses said they saw the gunman before the shooting and alerted authorities, Butler police said they had "responded to a number of reports of suspicious activity."

History of violence
Trump's narrow escape has also sparked conspiracy theories and fingerpointing by Republicans, as an already tense run-up to the elections becomes increasingly febrile.

Possible Trump vice presidential pick J.D. Vance said Biden's "rhetoric" had "led directly" to the Trump attack.

The attack happened days before the Republican National Convention in Milwaukee where Trump will be formally anointed as presidential candidate. Trump said he looked "forward to speaking to our Great Nation this week from Wisconsin."

Trump was treated in hospital and could later be seen walking unaided from his plane, though his wounded ear was not facing the camera in video footage posted by his deputy communications director. The New York Times reported that he was staying the night in New Jersey.

The United States has a history of political violence. President John F. Kennedy was assassinated in 1963 while President Ronald Reagan was shot but survived an assassination attempt in 1981.

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