GRAHAM, Texas -- If you measure a man by the mark he makes on others, then Harrison Brown was, perhaps, beyond measure.

"I think everybody lost a piece of their heart when they lost Harrison," says close friend Jeff Hazlett.

It was an unimaginably painful day at Graham High School Tuesday, as news spread that the 2016 graduate had been killed. He was stabbed, seemingly at random, on the campus of the University of Texas in Austin, where he was a freshman. Another UT student was arrested for the stabbing, which also left others injured.

"We knew today was going to be a hard day," says Harrison's former band teacher, Dax Freeman.

Freeman recalls a young man, involved in nearly every aspect of student life -- drama, choir, track, trumpet, to name a few of his activities. He was voted Senior Class Favorite and Mr. GHS.

"Harrison's one of those kids you wanted your kids to be like," Freeman says.

Students at Graham HS wore orange in his honor Tuesday.

"He was a friend to everybody," says Hazlett. "Anybody he met, they were friends." Hazlett, along with fellow junior Ryan Karper, considered Harrison a best friend. They say he was studying neuroscience, so he could help people like his father, who has ALS.

"The whole town is devastated. Just absolutely-- just devastated by the news," Karper says.

At a sunset vigil in the school's stadium Tuesday evening, more than 500 people honored the 19-year-old's memory.

The school choir sang Amazing Grace while others hoped the occasion reminded folks what is really important.

"What we take away from this is love hard. Love your loved ones," said Joe Gordy, the school's principal.

For his closet hometown buddies, it was a chance express their emotions.

"I would’ve told him I loved him, that he was like a brother to me," Karper says.

A mark left on others won't soon fade away.

Funeral arrangements are pending but will likely be this weekend.