Thousands of people ran from Brooklyn to Manhattan Sunday in honor of 9/11 first responders for the 18th annual Stephen Siller Tunnel to Towers 5K.

The event kicked off at the Brooklyn side of the Hugh L. Carey Tunnel in Red Hook.

The run retraces the path of FDNY Firefighter Stephen Siller, who grabbed his gear and ran to ground zero on 9/11, where he later died.

The route takes participants through the tunnel to the former site of the World Trade Center.

The run first started with 1,500 people. But now, upwards of 30,000 people take part in the run to honor first responders.

Proceeds of the run go to families of first responders. The organization is also raising money to help service members pay off mortgages and construct 50 mortgage-free homes.