At 8:46 a.m. Sunday, exactly 10 years later to the minute, firefighters and civilians across the country will climb 110 flights of stairs to honor and remember the 343 firefighters who died while responding to the terrorist attack on the World Trade Center’s twin towers.

In the Washington area, groups from Prince William and Prince George’s counties will host the event for the first time. They’ll climb, many in full gear, 110 stories — the equivalent number of flights in each of the twin towers — while carrying the name of one or more of the fallen New York firefighters.

Nick Kelly, a Marine and volunteer firefighter at Stonewall Jackson Volunteer Fire and Rescue, will be part of a three-man team climbing in full gear with air packs and tools.

“The event speaks for itself,” he said. “It’s pretty significant personally and professionally.”

The 9/11 Stair Climb began in 2005 when five Denver firefighters climbed 110 stories to honor those lost in New York. The event is now in 25 states and Canada.

Amy Tarte, a firefighter at the Stonewall Jackson station, heard about the event last spring during a conference in Indianapolis.

Immediately she thought, “We can get that going in Manassas.”

She mentioned the stair climb to Jenny Holden, an emergency medical technician at the station, and the idea spread like wild fire.

Tarte said the main purpose for the Manassas Stair Climb is to bring people together to remember and recognize the firefighters who died Sept. 11, 2001. But, she said, “it’s not just the 343. It’s for all the firefighters lost every year.”

It will also be the first climb for the Prince George’s County fire and rescue department.

Kellie Bornman, an almost 40-year veteran of the Boulevard Heights Volunteer Fire Department, said she came across the idea last year while on Facebook. She pitched the idea to her fellow firefighters, and they immediately formed a committee to begin planning this year’s event.

“I thought this was such a wonderful event and something P.G. County should get involved in,” she said. “We will never forget the sacrifice they made to save others.”

In Greenbelt, close to 100 firefighters and civilians will ascend the Maryland Trade Center. Bornman said it seemed a fitting location, because it “closely” resembles the World Trade Center towers.

Finding a building that was tall enough was a problem for the Manassas crew. Although they considered moving to a larger building outside the county, they decided to stay in Manassas and climb the nine story Sudley Tower.

With the support of building management, Manassas participants will use both stairwells and climb the tower 12 times with two extra flights to make 110 stories.

The Manassas climb will be divided into teams to help with motivation, and because that’s how the fire department works, Holden said.

“You enter the building together. You leave the building together,” she said.

Registration and check-in begins at 7 a.m. in Greenbelt and at 7:15 a.m. in Manassas. The registration fee is the same for both sites, $25.

In Manassas, an opening ceremony will follow registration with a moment of silence to remember those who are being honored. Bagpipers from the Northern Virginia Emerald Society Pipe Band, including Tarte, will perform, and the climb will last until the final climber descends the tower.

In addition to the climb, the Prince George’s fire department will also host a three-mile walk that day. The three miles represent the three locations attacked on Sept. 11, 2001, Bornman said. To participate in the walk costs $15.

Proceeds from the events benefit the National Fallen Firefighters Foundation, created to honor fallen firefighters and provide support for their families.

Larry Price, a Stonewall firefighter and EMT, said 9/11 was one of the reasons he joined the fire and rescue department seven years ago. As he was training for the upcoming climb, he said, “We’ll try to honor the firefighters who died.”

For information about the Manassas 9/11 Stair Climb, visit www.manassasstairclimb.com.