NEW YORK (CBSNewYork/AP) -- The sun shone brightly Sunday morning as the 25,000 people participating in the annual Tunnel To Towers 5K run in Lower Manhattan.
More than 25,000 people registered to participate in the run, which honors firefighter Stephen A. Siller, who lost his life responding to the 9/11 attacks 15 years ago.
"So much has happened within the last 15 years and we can't believe that this is the 15th anniversary," said Frank Siller, Stephen Siller's brother and the chief executive officer of the Stephen Siller Tunnel to Towers Foundation.
On Sept. 11, 2001, Siller was off-duty, and on his way to meet his brothers to play golf when his scanner alerted him to the attacks on the World Trade Center. He turned around and grabbed his turnout gear instead of his golf clubs and raced to the burning towers. His truck was stopped at what was then known as the the Brooklyn Battery Tunnel, undaunted he strapped on 60 pounds of gear, and ran through the tunnel and into history.
"That's my brother. He was always looking to help people out. I'm sure he was thinking about his family as he was running to the towers, but his duty overcame everything," said Stephen Siller's brother, George Siller.
The foundation was formed in Stephen's honor. They started the Building for America's Bravest program, which designs and constructs homes for the most critically wounded soldiers. The uber high-tech homes allow heroes to be in their homes alone and regain control of their lives.
On Sunday, some participants were dressed in firefighter uniforms, with helmets that bore American flags, WCBS 880's Sophia Hall reported. Others, like Giovanna Repka, 16, had a pin attached to her jacket to honor those lost on Sept. 11.
"My great-uncle was lost on 9/11," Repka said. "I've always wanted to do something great and I feel like this is just one step."
Frank Siller told 1010 WINS' Samantha Liebman he was excited to see such a record turnout 15 years after his brother Stephen's death.
"The further you get away from it, you want to make sure people don't forget, and we continue to honor all those who were lost that day."
The event showed the resiliency of New Yorkers, who were hit with another terrorist attack one week ago. A bomb injured more than two dozen people when it detonated in a Chelsea dumpster.
With that in mind, safety concerns were front and center after the Chelsea bombing, as well as an earlier one the same day in Seaside Park.
Tunnel To Towers 5K Run Guide: Race Information, Registration, More
Participants saw a heightened security presence, with officers at various checkpoints. Book bags were not allowed and police regularly inspected trash cans in the area.
Many runners who had planned on participating in the cancelled Marine charity run in Seaside Park also ran in Sunday's event.
About 100 runners joined in the race after a pipe bomb explosion canceled their race in Seaside Park, New Jersey last week.
The runners wore matching white shirts and held hands at the starting line of the Tunnel to Towers Run on Sunday morning.
They had been planning to take part in the Semper Five charity 5K in Seaside Park, New Jersey, on Sept. 17. That race was halted after the bomb went off. No one was injured.
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