Orlando gunman Omar Mateen jumped up and down and cheered as the Twin Towers fell on 9/11, former classmates have revealed.
One classmate told the Washington Post that after the attacks, Mateen seemed to make fun of how America was targeted.
“He was making plane noises on the bus, acting like he was running into a building,” Robert Zirkle told the newspaper. “After 9/11 happened, he started changing and acting different."
Another student reportedly remembered Mateen smiling and said he claimed Osama bin Laden was his uncle.
One of Mateen's former colleagues, Dan Gilroy, said he was also troubled by the gunman.
"I felt that he had the propensity for violence, absolutely," Gilroy told Inside Edition. "He spend most of the time complaining and railing and insulting and threatening to murder women and blacks."
He said he also heard Mateen make derogatory comments about homosexual and Jewish people.
Officials say Mateen pledged allegiance to ISIS in a phone call to 911 during Sunday's attack, which left 49 dead and 53 injured.