The Towers to Tunnels 5K Run and Walk kicked off in Brooklyn Sunday with thousands of runners taking part.

Firefighters and children of all ages ran with their families to honor lives lost on 9/11.

Runners went through the Hugh Carey Tunnel to get to the World Trade Center, where lives were lost 21 years ago. Many people wore the pictures of their loved ones that have still not been found.

The event pays tribute to the 343 firefighters and first responders lost that day and has expanded to honor all the lives lost in the War on Terror.

One runner was a firefighter hired just days before the attack in downtown Manhattan.

“I run now because I have to show respect…I lost a lot of my buddies on that day,” says firefighter Allan Hagander.

The 5K run also honored the 13 lives that were lost on Aug. 16, 2021 during the United States’ withdrawal from Afghanistan.