HAWAII KAI, Hawaii - A group of Marine firefighters trekked up Koko Head Crater Stairs on Wednesday to honor of the first responders who died during the terrorist attacks on Sept. 11, 2001.

They started the annual 9/11 Memorial Stair Climb just after sunrise. The men are part of the Airfield Rescue and Fire Fighting team stationed at Marine Corps Base Hawai'i. Several of them carried ammo cans full of sand to make the climb more challenging. The tribute is a tradition they've been doing since 2016.

"Our brothers and sisters on 9/11 ran into those unknowns and they paid that sacrifice," said Warrant Ofc. Jacob Forston. "We picked this [hike] because it hits the spirit of the event of hitting the challenge firefighters experienced on 9/11. So it's just to pay tribute to them and their sacrifice."

Forston added, "This isn't just for the firefighters, this is for all the emergency responders. I use firefighters because that's what we do, but this is for all the police officers that were there, the emergency responders that were there, everybody who ran in that didn't have to. This is for all of them." 

343 firefighters died while responding to the attacks. In the 18 years that followed, more than 200 additional firefighters have died of 9/11 related illnesses, according to ABC News.