DANIA BEACH, Fla. -- Two self-defense instructors are dealing with the frightening possibility that they may have taught a hijacker how to kill.

Bert Rodriguez (pictured), an eighth-degree black belt, and Carlos Goni were two of the trainers who taught suspected hijacker Ziad Jarrah self-defense techniques.

Jarrah is believed to have taken over the flight that crashed in Pennsylvania.

"He wanted to learn knife techniques, gun techniques. He even asked me, 'Do you mind. I'll bring in a plastic gun.' He's like, 'Just show me techniques," Goni said.

"It hits you hard that you would even have to be (part of it). Of all the people in the world that could of been picked why the hell did they pick me?" Rodriguez said.

Despite that training, investigators believe that the passengers on that flight fought the hijackers, causing that plane to crash in a field before it could reach its intended target.