Thousands of runners laced up their sneakers and hit the pavement Sunday to honor those who lost their lives in the Sept. 11 attacks.

The 13th annual Tunnel to Towers 5K Run/Walk drew an estimated 30,000 people from across the globe. The race stretched from the Brooklyn-Battery Tunnel into Manhattan in honor of Brooklyn firefighter Stephen Siller.

The run follows the same path that Siller sprinted on the morning of the attacks, lugging his gear the entire way. He did not survive the attacks.

Although the race is named after Siller's courageous deed, runners remember everyone who perished. Runner Lisa Kelly said she participated to honor four of her colleagues from New York Presbyterian Hospital who had died.

Flanking all sides of the Battery Tunnel were 6,836 American flags, representing the fallen servicemen and women who have died since Sept. 11.