Thousands of runners and walkers retraced the steps of an American hero in Lower Manhattan Sunday morning during the 12th annual Tunnel to Towers Run.
The race was inspired by New York City firefighter Stephen Siller who, on September 11, 2001, ran through the Brooklyn Battery Tunnel to the World Trade Center in full gear to reach those in need.
He later died when the South Tower collapsed.
"I'm sure what he thought was he'll help a lot of people out and he'll get out but that didn't happen," said Siller's brother, Russ Siller.
The annual run also pays tribute to the 343 firefighters lost that day, as well as police officers, EMTs, and military veterans.
More than 25,000 people ran along the same three mile route that Siller ran to help raise money for a wide range of children's, community, and veterans charities.
Some participants say following in Siller's footsteps was an exhilarating experience.
"It was awesome. It's sick, you're going through the tunnel. First of all you're hot, you're sweating, everyone's cheering USA. It's awesome," said one runner.
"I came out here to honor Stephen Siller. I work near the memorial and I see his name all the time and the whole year I spent trying to make sure our team was a lot larger than it was last year," said another runner.
The run started in 2002 with only about a thousand participants. It's now held in cities around the country and around the world, as far away as Afghanistan.
For more information, visit tunnel2towers.org.