L.A. City Fire Department Assistant Chief Steve Hissong, firefighter Bubba Willis and Captain Robby Cordobes share a bond.
"We were the fortunate ones that were able to do what millions of people wanted to do," said Willis.
They were members of FEMA's Urban Search and Rescue team, assigned to California Task Force One. The tragic event was what they had trained for and the deployment was their first.
"I don't think we were quite ready to see the devastation of what happens when those towers collapsed," said Hissong. "There literally was such devastation, everything was dust."
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Saturday marks 20 years since the attack, and the firefighters recall one of the most intense things being the pictures and posters that people plastered in the area looking for their missing loved ones.
"That's when it really became real to me, the magnitude of how many people were missing, the magnitude of the area that we were searching, the magnitude of how many people were all searching at the same time," Hissong added.
While there's an emotional toll related to their response, there are physical scars as well.
Willis manages his health issues with help from a World Trade Center medical program that was created for first responders.
One of their team members, Tom Burau, passed away last year from what was identified as 9/11-related cancer. They think about him, and their 11 days at ground zero often.
"The big thing is never forget," Willis said.