The  Federal Bureau of Investigation (FBI) has officially identified the man who attacked former US President Donald Trump during a rally in Pennsylvania as 20-year-old Thomas Matthew Crooks whose former classmates described him as a 'quiet' boy who faced bullying in school.

The FBI said in a statement: " The FBI has identified Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania, as the subject involved in the assassination attempt of former President Donald Trump on July 13, in Butler, Pennsylvania."

The FBI said the shooting incident is still under investigation.

The FBI did not reveal the motive behind the attack.

Several images of the attacker are now making the rounds on social media.

Thomas Matthew Crooks was a resident of  Bethel Park in Pennsylvania and he was eligible to case his vote in the upcoming Presidential polls later this year.

The shooter graduated in 2022 from Bethel Park High School with a $500 prize for maths and science, BBC reported.

Crooks, who reportedly was a registered Republican, worked in a local nursing home.

He donated $15 to liberal campaign group ActBlue in 2021, reported BBC.

So far, investigators haven’t found any evidence on social media or other writings by Crooks that might help identify his motive for the attempted assassination, law enforcement officials told CNN.

How former classmates described Crooks?

His former classmates described him as a 'quiet kid'.

Jason Kohler, 21, who went to the same high school, told CNN that Crooks was bullied by other students and seemed to be a loner.

Crooks had “no facial expression” when he walked through the school hallways, Kohler said. “He wasn’t, like, with the clique, so he always had, I guess, a target on his back.”

A third classmate, who asked not to be named, told CNN that Crooks was very smart, took honours classes, and was shy.

What happened during the rally?

Former US President Donald Trump received injuries on his right ear during a Saturday election campaign rally at Pennsylvania's Butler, in what is seen as an assassination bid that left the 78-year-old Republican presidential candidate's face streaked with blood with his alert security agents rushing him off the stage even as he pumped his fist in the air, mouthing the words "Fight! Fight! Fight!"

The shooter, along with one bystander who was there to attend the rally, died.

As gunshots were heard, Trump, who was just six minutes into his election speech, was seen clutching a hand to his right ear, where blood was visible across his cheek and mouth.

Two other spectators were injured, the Secret Service said in a statement. The incident was being investigated as an assassination attempt.

Secret Service agents were quick to respond and surrounded Trump while escorting him off the stage, as he raised a fist to the crowd in defiance.

Biden says no place for violence

US President Joe Biden reacted to the attack on Trump and said there is no place for such violence in the country.

"I have been briefed on the shooting at Donald Trump’s rally in Pennsylvania," Biden said.

"I’m grateful to hear that he’s safe and doing well. I’m praying for him and his family and for all those who were at the rally, as we await further information," he said.

"Jill and I are grateful to the Secret Service for getting him to safety. There’s no place for this kind of violence in America. We must unite as one nation to condemn it," he said.