More details about the Pennsylvania man who shot at former President Donald Trump, Thomas Matthew Crooks, have emerged. As it turns out, he is a registered Republican based on local voter data. He is also a big fan of a popular gun YouTube channel.

Crooks managed to kill one spectator and injured three others, including former President Trump, whom he managed to clip in the upper part of his ear. While Trump himself was OK, the two other spectators were in critical condition.

The FBI had revealed that Thomas Matthew Crooks was killed at the scene. The agency says that they are still trying to identify why he shot at the former president, saying that they did not "currently have an identified motive, although our investigators are working tirelessly to attempt to identify what that motive was."

Pittsburgh Special Agent in Charge Kevin Rojek stated that the agency has placed the highest priority on determining Crooks's motive, while Robert Wells, the FBI's assistant director of the Counterterrorism Division, has stated that the FBI is also looking at the shooting as a "potential domestic terrorism act."

Rojek told ABC News that officials believed that Crooks "acted alone and that there are currently no public safety concerns," and added that "At present, we have not identified an ideology associated with the subject, but I want to remind everyone that we're still very early in this investigation."

State voter records have revealed that Crooks had been registered as a Republican voter. He had graduated from high school in 2002 and had no military affiliation. He previously worked as a dietary aide at the Bethel Park Skilled Nursing and Rehabilitation Center, where he "performed his job without concern" and passed a background check.

Donald Trump Shooter Thomas Matthew Crooks Was 'Lonely' and 'Quiet,' Say Former Classmates

Meanwhile, his former classmates have been speaking up to the media and talking about Crooks, with many of them describing him as a "quiet" loner who did not have that many friends.

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"He was somebody who came across as lonely a lot," said former classmate Jameson Myers, adding that the Donald Trump shooter "tended to be more of an interesting one" and described him as "more socially reserved."

When he tried to shoot Trump, Crooks was wearing a T-shirt from Demolition Ranch, a firearms and explosives YouTube channel with millions of subscribers. The YouTuber behind the channel, Matt Carriker, reacted to the revelation with a post on X saying, What the hell."

Joe Biden Appeals for Unity After Donald Trump Shooting

Meanwhile, President Joe Biden, who was running against Trump, quickly ordered attack ads to be canceled amid the Trump assassination attempt and then called for unity, saying that the incident "is contrary to everything we stand for as a nation."

"It's not who we are as a nation. It's not American. And we cannot allow this to happen," he said in his televised remarks. "Unity is the most elusive goal of all, but nothing is more important than that right now."

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This article is owned by Latin Post.

Written by: Rick Martin

WATCH: Suspected Trump shooter identified as Thomas Matthew Crooks: What we know - FOX 5 New York