Eleven years ago, 343 New York City firefighters, many of them climbing stairwells full of smoke, soot and people trying to escape, were killed when the World Trade Center towers collapsed following the worst terrorist attack in America.

Eleven years ago, 343 New York City firefighters, many of them climbing stairwells full of smoke, soot and people trying to escape, were killed when the World Trade Center towers collapsed following the worst terrorist attack in America.

The terrorist attacks that day left nearly 3,000 people dead and a nation stunned and in mourning. As a way to remember the anniversary, and honor the firefighters killed trying to save others, a event was held in Oklahoma City over the weekend.

Oklahoma firefighters, including five from the Tecumseh Fire Department, participated in the grueling, yet challenging Oklahoma City 9/11 Memorial Stair Climb.

Each firefighter, wearing full bunker gear and air packs, climbed 110-stories in honor of the FDNY 343.

Tecumseh Fire Chief Aaron Williams said it was both an emotional and memorable experience.

"Honestly, it was one of the most exhausting and physical tasks I have ever taken on," Williams said. "But I wouldn't trade it for anything — it was well worth signing up for us — it was definitely a great accomplishment."

The event took place at the First National Center in Oklahoma City. Without a tall enough building for all 110 floors, the climb involved fire crews going up 29 floors three different times, then up 22 more floors and one more to make 110 floors, he said.

Tecumseh Lt. Shane Brown, along with Firefighters Greg Shirey, Kim Condit and Cody Young also participated in the climb.

Williams said he and about 139 firefighters from departments around the state walked the stairs to honor the 343 firefighters killed that day. Each of them carried two, and some three, tags with the names of firefighters to honor.

With full firefighter gear already adding an additional 50 to 60 pounds, Brown and Young also took turns carrying a high-rise pack of extra hoses, which added even more weight to the stair climb, Williams said.

"It wasn't a race — it was to honor those guys and complete the climb they weren't able to," Williams said.

Brown, who said the high-rise pack did add some weight, said he handed it off at times to Young, and to firefighters from other departments who saw it and wanted a chance to carry it too.

And while it was challenging, Brown said the event was nothing compared to what the firefighters endured on 9/11.

"This is nothing — they had ash and smoke coming down on them," Brown said, adding he and others had many such conversations in the stairwells on Saturday.

And despite the pain and exhaustion, their time also was a chance for firefighters to unite and strengthen that camaraderie bond.

Shirey said it was an emotional event to go through.

"To think they had no choice," he said, adding the exhaustion was just overwhelming.

"I wanted to honor them," Shirey said, adding it was a very touching event and he was glad for the opportunity.

Firefighter Cody Young, who at 18 is the youngest of them to participate, said it was even challenging for him as he couldn't believe the work involved for 110 stories, which put a perspective on what the crews endured that day 11 years ago.

Young, who was in elementary school on Sept. 11, 2001, said he remembers being at school and knowing something bad had happened, but said it took a couple of years before he fully understood.

This year, as a new volunteer firefighter, he had the chance to both honor his fellow firefighters who died as well as gain perspective on the scope of what happened that day.

"It was a representation of what it all meant," Young said, adding he said he wants to participate again next year.

For Condit, one of a handful of female firefighters participating, the event was something she'll never forget.

"It was pretty amazing on how many showed up and the support among firefighters," Condit said. "Everyone was cheering each other on — it was hard."

Through it all, she had one thing on her mind.

"These people gave up their lives so what's 110 stories?" Condit said, adding she pushed through the physical exhaustion as well. "It's something you never forget."

All proceeds from the climb benefited the Oklahoma City National Memorial, The National Fallen Firefighters Foundation and FDNY.

The first 9/11 Memorial Stair Climb event occurred on Sept. 11, 2003 during "Operation Enduring Freedom" in Parwan Province, Afghanistan.

Then on Sept. 11, 2005, five Colorado firefighters gathered in downtown Denver to climb 110 flights of stairs in all their gear in memory of their FDNY brothers who were killed four years earlier in the terrorist attacks of 9/11.

The event grew year after year and in 2009 and in 2010, founders of the Denver 9/11Memorial Stair Climb partnered with the National Fallen Firefighters Foundation (NFFF) to set forth the national standard protocol for future 9/11 Memorial Stair Climbs across the nation.

An Oklahoma firefighter participated in the 2011 Dallas Stair Climb and decided to bring it to Oklahoma City for the first time this year.

Williams said he hopes Tecumseh firefighters will participate each year.