Tyler Robinson's Former Classmate Speaks Out, Says He Wasn't a Loner

Tyler Robinson's classmate is speaking out in the aftermath of his arrest in connection with Charlie Kirk's death ... sharing that the kid he remembers was a smart and goofy one, not a possible cold-hearted killer.

We caught up with the suspected shooter's classmate -- who chose to remain anonymous -- on "TMZ Live" Friday, mere hours after Robinson was apprehended and named as the main suspect in the fatal shooting of the conservative pundit.

And, as the classmate told us, he found the news "extremely shocking," as he couldn't believe someone he went to middle school and high school with could possibly be culpable for this kind of violence.

Per the classmate, Robinson wasn't a loner at school by any means ... though, they did note that TR was "very online," knowing memes and such.

While the schoolmate clarified he wasn't particularly close with Robinson back in the day, he said he didn't recall Robinson being particularly interested in guns or super political.

In short, there were no warning signs that he might one day be a murder suspect.

As we reported, Robinson was arrested and booked on aggravated murder and weapons charges Friday -- 2 days after Kirk was shot in the neck while speaking at Utah Valley University.

While Donald Trump was the first to break the news on "Fox & Friends" Friday morning, Utah Governor Spencer Cox later held a press conference ... revealing Robinson was arrested after his father tipped off a family friend that TR may've been the shooter.

As mentioned in the press conference, Robinson had allegedly become more political lately, and even mentioned Kirk's upcoming visit during a family dinner prior to the shooting.

Authorities have confirmed recovered bullet casings had messages inscribed on them ... including, "Hey fascist, catch," "Bella Ciao," and "If you read this you're gay, LMAO."