NEW YORK (PIX11) – The 21^st Tunnel to Towers 5K is happening this Sunday in New York City. The annual event was created in honor of the late Stephen Siller, an FDNY firefighter who ran through the formerly named Brooklyn-Battery Tunnel on 9/11 to rescue people from the burning towers.

Frank Siller, Stephen’s brother and CEO and Chairman of Tunnel to Towers Foundation, says the 5K symbolizes his last footsteps as he wore 60 lbs of his gear rushing to the World Trade Center.

"As a family, we decided that we were going to start this foundation in honor of him, but honestly, we wanted to make sure, from the very first run, that we honored all those who perished that day but most certainly our first responders,” Frank said.

The first run consisted of 1,500 participants, and now, about 35,000 people join in remembering those we lost on 9/11 and the years after, both at Ground Zero and around the world. Every year, the foundation honors our military, too, because more than 7,000 service members have their lives to our country since Sept. 11, 2001.

This weekend, the 13 service members killed in Afghanistan while U.S. troops withdrew last year will be honored.

"Six of those families are going to be joining us,” Frank said. “We’re going to read those names out loud, and we’re going to make sure they realize that they're part of those names that we're never going to forget."

Country singer Dierks Bentley will also be performing.

Frank often visits the 9/11 Memorial pools in Lower Manhattan, where his brother's name is inscribed. He knows the firsthand feeling of a loved one not making it home, so the foundation helps families of first responders nationwide by paying off their mortgages.

"They go out every day, they give their kids a kiss goodbye, and if they don’t come home, Tunnel to Towers Foundation is going to be the foundation that takes care of them,” Frank said. “If they don’t have a home, we build them a home, mortgage-free. So for our catastrophically-injured service members or first responders that give their bodies for our country, we're going to give them a mortgage-free smart home."

The foundation says its Smart Home Program “builds specially adapted mortgage-free homes that help our nation’s most catastrophically injured veterans and first responders reclaim their independence in carrying out day-to-day activities around the home.”

These gestures are made possible because of events like the 5K and the generosity of Americans, especially New Yorkers, who join in on the mission.

If you’re interested in participating in the 5K, you can run or walk the entire distance while supporting first responder families. You can register until 8:29 AM on Sunday, Sept. 25, by visiting the Tunnels to Towers website.