Retired New York City Fire Lieutenant Paul Geidel didn't watch the twin towers come down in real-time on television. He didn't hear about it on the radio.
He was taking a road trip, and it wasn't until he stopped for food that a sandwich shop employee told him the worst news of his life.
"She explained a plane had hit the towers, and I didn't believe her at first," Geidel said.
Two of Geidel's sons were working as firefighters in New York City at the time. He knew they were likely in the towers, and he knew the prospects might be terrible.
"It was horrible," he said.
Geidel was never able to find his son Gary. For eight and a half months, he and his family searched through the rubble and found no trace of him.
Years later, Geidel would lose his son Ralph. He believes Ralph fell ill breathing in the toxins at the World Trade Center site.
"I wish it was me instead of them," he said. "I miss them so much."
As the 16th anniversary of that tragic day gets closer, Geidel is finding a way to give back.
He recently published a book titled "Into Harm's Way" which recounts his life, including the search for his son after the towers collapsed.
Geidel said the proceeds will be given to the Remembrance Rescue Project to help ensure future generations never forget what he, and so many others, lost on that day.
"It isn't only my son Gary and my son Ralph, it's all those other poor souls, thousands of people. It's important. How could you possibly forget it?," Geidel said.
The Geidel family legacy still lives on. His third son, Michael, continues working as a firefighter in New York City today.