"I made two passes around it [ground zero], and I still couldn't get my head around the size of it," said Menlo Park Fire Chief Harold Schapelhouman. He thinks about the sights and sounds of ground zero all the time, and the smells -- the acrid smells of smoke and dust and the smell of death.
"The smell, the sights, those things, they never leave you, and there's things you come across once in a while that recreate that and make you think about it," said Batt. Chief Frank Fraone.
But when they got to the scene just days after the attack, there was no room for emotion. Crews snapped into action searching for hotspots, then looking for survivors, and then recovering bodies.
"You learn to not become emotionally attached, but you're certainly attached to what you're doing," said Shirley Hammond who searched for bodies at ground zero with her specially-trained dogs. Her husband Dave is a safety engineer who tries to determine what is safe and what is not for the teams. Later, during downtime, the Hammonds thought about what surrounded them -- the planes slamming into the buildings, the thousands of lives lost. They were glad they were not apart.
"My answer to that is that we have each other and so it's a shared experience," said Dave Hammond.
The experienced changed everyone. Both firefighters and civilian search teams made new friends in New York. They also learned how resilient people can be in the wake of disaster.
Some also brought breathing problems. Chiefs Fraone and Schapelhouman both take medication for it, regardless they say they'd do it all again.
"I always will be proud that I was one of the responders in 9/11," said Schapelhouman. "I know all of our people would tell you the same thing."