TUCSON, Ariz. (KOLD News 13) - As the nation marks 18 years since the Sept. 11 attacks, people across Tucson spent Wednesday morning remembering those who gave the ultimate sacrifice.
Many gathered at Arizona Stadium for the 9/11 Tower Challenge.
They climbed 2,071 steps to honor the more than 400 first responders who lost their lives in the 2001 terror attacks.
The number of steps represents the amount of stairs in the 110-floor twin towers, where most of the people who were killed that day were located.
Nearly 3,000 people were killed in coordinated attacks in New York, Washington, DC, and Pennsylvania.
In the years since, many others have died as a result of exposure to toxins and debris from the fallen towers.
Many of Wednesday's Tower Challenge participants included firefighters in full gear, police and military members with there friends and families.
Photos of the fallen heroes were placed along the stairs of the stadium as a tribute to them and an inspiration to the climbers.
Money raised from the Tower Challenge will go to help first responders and military families.