Former David Katz Classmate Speaks out About Jacksonville Shooter

A former classmate of David Katz is speaking out about the suspect in Sunday's deadly shooting in Jacksonville, Florida.

Katz stormed into the Madden NFL 19 video game tournament and allegedly opened fire on the assembled crowd. Two people were killed and nine injured in the attack. Now, Kevin Osai has opened up about his former high school classmate and the shock of the tragedy.

"He was always a quiet guy, never had any altercations I could remember," Osai told Roxanne Feitel of CBS Interactive. "He wasn't winning popularity contests, but he had no enemies, etc."

Osai felt that, during his time in high school with Katz, there was nothing to indicate that he had the capacity for this kind of violence.

"I wouldn't say that any specific behavior would point me or lead me to ascertain that we may have been able to predict/stop this," he added, "maybe there was something more to his usually disinterest in school then what we all felt most days."

However, Osai did recall Katz having a considerable temper, and remembered that he was generally slow to calm himself after it flared up.

"I'll note that if he was angered, it took him a while to cool down," he said. "I remember that one day when one of his friends had made a joke on him in front of others and he really took it to heart. Nothing came of it at the time, but reflecting now I could see him eventually lashing out from that shell he kept himself in."

Osai pondered steps to set Katz straight early on. He speculated on how the faculty or student body could have course-corrected Katz as a young man, before something like this happened.

"I think he needed more guidance even then," Osai said, "as he was seeing the school counselor regularly when we were in [high school], a lot of us keep in contact and are in complete shock over this — quiet, sure. But vengeful cold blooded killer? Who radicalized him ..."

The question, one of many facing investigators, likely does not have a simple answer. Katz died on the scene of the shooting, suffering from self-inflicted gunshot wounds, according to a report by CBS News.

The 24-year-old was from Baltimore, Maryland, and within hours of the attack his father's home in the city was raided by FBI agents.