Two of them, Port Authority Police Officer Will Jimeno and his sergeant, John McLoughlin, were trapped for 12 hours before they were rescued.
Oliver Stone's new movie, "World Trade Center," tells their stories.
Jimeno is played by Michael Pena. He co-stars with Nicholas Cage, who portrays McLoughlin.
On The Early Show Tuesday, Pena told co-anchor Hannah Storm that spending much of the film pinned and immobile was well worth it.
"Regardless what I went through, I was just trying to tell his (Jimeno's) story, and the fact that there was something — when I read the script, I didn't know if it was real or not. I didn't know if it had actually happened."
Pena says he wasn't sure whether Jimeno existed or was a composite character, "and then you meet him, and you're like, 'Absolutely! This guy is like a home-run hitter, an all-around good guy!' "
Jimeno insisted to Storm that he thinks "everybody's like me. I don't think I'm different than anybody else. I would hope everybody is a positive person. I'm a byproduct of my parents, who always told me to be a positive person and be good to people. So, I'd like to assume everybody is a good person and happy-go-lucky person."
Jimeno told Storm, "My sergeant and me, when they first approached us about the film, we were looking at them like, 'Why us?' We didn't really understand.
"It really took a meeting with (producer) Debra Hill, who really got the ball rolling on this project and, unfortunately, last year passed (away), and she's an angel looking down on us. She really showed us more than what me and my sergeant wanted to do, which is really to honor our teammates and the guys we consider our heroes for coming in to get us.
"But she saw the bigger picture, the strength of our wives and just humanity in general. After talking to her, we said we'd continue with this project and see where we go, and we just kept meeting more and more good people who had good intentions."