Trump was left with a bloodied face after a bullet pierced the upper part of his right ear.
The gunman who shot at former president Donald Trump during an election rally in Pennsylvania on Saturday appears to have acted alone, said the Federal Bureau of Investigation (FBI), which is probing the incident as a potential "domestic terrorism" act.
The gunman, shot dead by a sniper, has been identified as Thomas Matthew Crooks (20).
"At this point in the investigation, it appears that he was a lone actor, but we still have more investigation to go," said Robert Wells, the executive assistant director of the FBI's National Security Branch.
The FBI, he said, is investigating this as an assassination attempt and also as a "potential domestic terrorism act". The counterterrorism division and criminal divisions are working together to determine the motive, he added.
Trump was left with a bloodied face after a bullet pierced the upper part of his right ear. He is now safe and continuing with his schedule that includes travelling to Milwaukee to attend the Republican National Convention, which would formally nominate him as the party's presidential nominee against incumbent Joe Biden.
The FBI is leading the investigation into the assassination attempt.
"The shooter may be deceased, but the investigation is very much ongoing. And, because of that, we are limited in what we say at this point," FBI Director Christopher Wray said.
"What we witnessed yesterday was nothing short of an attack on democracy and our democratic process," he told reporters at a news conference in Washington DC.
According to an FBI official, the investigation into the gunman at Donald Trump's rally Saturday has not yet turned up any mental health issues, threatening posts, or other motives, but cautioned it was still early.
The shooter, as per FBI, used an AR-style rifle chambered in 5.56mm, a common calibre for such weapons.
The New York Times said authorities were scouring the gunman's social media and other property as they sought to determine a motive for the attack.
Biden is likely to address the nation at 8 pm from the Oval Office. He will give "a forceful and needed address to update the nation on the horrifying attack on Donald Trump and the need for every American to come together to not just condemn, but put to an end political violence in this country once and for all," a campaign official told the daily.
Crooks graduated from the Community College of Allegheny County two months ago, earning an associate degree in engineering science, school officials said in a statement, adding that they were "shocked and saddened by the horrific turn of events."
Kimberly Cheatle, the director of the Secret Service, in a memo to her agents, said "The attempted assassination of former President Trump in Butler, Pennsylvania, is a moment that will forever be remembered in history."
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