Thomas Crooks' former guidance counselor says his "stomach sank" hearing news

BETHEL PARK, Pa. (KDKA) -- The former guidance counselor of Bethel Park native Thomas Matthew Crooks , the would-be Trump assassin, says he was shocked to hear about the shooting.

The 20-year-old opened fire with an AR-style rifle from the roof a building outside of the security perimeter of the Trump rally Saturday in Butler County.

"When I first heard it was Thomas, it didn't register," former Bethel Park guidance counselor Jim Knapp said. "So, I actually had to go back and look up some pictures that I was able to keep from when I was a guidance counselor, and some notes that I took myself and therefore I was able to look at those notes and look at his picture. And therefore, it started to all come back, the recollection all came back. And when I recognized who it was and what happened, it just made my stomach sank. And my heart went out."

Crooks attended Bethel Park High School. During his sophomore year he started seeing Knapp. The former guidance counselor said he didn't see any bullying.

"I really want to emphasize that we took great pride -- and I say we, I mean the counselors, the administration and the school district -- took great pride in trying to avert or trying to stay away from any bullying situations," Knapp said.

So far, Crooks' motive in the attack on the former president remains unclear. The shooting killed 50-year-old firefighter Corey Comperatore , injured two others and hit the former president in the ear.