Thousands descend on Colorado's Red Rocks to honor first responders for 9/11

Thousands of emergency responders and the community gathered at Red Rocks Amphitheatre for a stair climb in remembrance of those who died in the 9/11 terrorist attacks 25 years ago. 

Founder of the 9/11 Stair Climb Shawn Duncan says there are 4,000 people from across 35 states and the Netherlands who came to Red Rocks for the stair climb. Among the attendees are firefighters, EMS services, police, and military members. There are also community members who came with their families for the climb. 

One group includes cross-country runners from Windsor who decided to participate.

"It was really traumatic, but it's an honor to come here and do the memorial," said Alexis Bailey with Windsor Cross Country.

Duncan also says for those who were not alive during the 9/11 terrorist attacks still came to do the climb, in remembrance of those who died.

"One of the most important things we can do is to keep this fresh on people's minds," Duncan said. "Part of keeping that promise of never forgetting is getting to the younger generation and the people who were not around, the people who don't remember what happened that day and why we honor them."

Duncan says that since the stair climb began 18 years ago, they have raised more than $15 million for firefighter services.