NEW YORK (CBSNewYork) — A thousand people climbed the stairs of North America’s tallest skyscraper Sunday morning to raise money for badly injured members of the service.

Competiting in the first-ever Tunnel to Towers stair climb at 1 World Trade Center, the participants raced up 1,970 stairs to the 90th floor.

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It took John Theissen 16 minutes.

For him, it was a somber event. He lost several close friends in the 9/11 terrorist attack.

“I can’t look at this as so much like a race and I want to be competitive and beat my competitors, but more of a moment just to reflect on what happened,” he told 1010 WINS’ Carol D’Auria. “I’m doing it for the people that can’t, that lost their lives.”

The climb was organized specifically to remember fire Capt. Billy Burke, who died on 9/11.

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The event raised $500,000 to buy a “smart house” for a service man or woman who suffered catastrophic injuries abroad fighting terrorism. Participants had to pay $100 to enter and raise at least $250 each.

Bruce Miller, a competitive stair climber from Scarsdale, kept thinking of the firefighters and all the gear they carry when they respond to a fire or some other emergency.

“I was thinking everyone’s complaining how hard it is, and I’m picturing what it would be like to be carrying a backpack of 100 pounds,” he told WCBS 880’s Ginny Kosola.

Lynda Hubbard, of Oceanside, said it was more than just another competitive climb.

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“It’s an iconic building,” she said. “This is the first time doing it. To get to the top just makes you feel thankful for being able to do it and just remembering 9/11. Never forget.”