A video has now surfaced on social media where the attacker, who tried to assassinate ex-President Donald Trump, could be seen allegedly bullied by his classmates.

In the video, classmates could be seen allegedly bullying 20-year-old Thomas Matthew Crooks.

They were seen pulling his pants.

The  Federal Bureau of Investigation (FBI) earlier officially identified the man who attacked former US President Donald Trump during a rally in Pennsylvania as 20-year-old Thomas Matthew Crooks.

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.

Crooks was shot dead by the law enforcement.

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.

(Note: IBNS could not independently verify the authenticity of the video)