Dave Quesada wasn't old enough to be a firefighter on Sept. 11, 2001.
But the story of Stephen Siller -- an FDNY firefighter who perished in the Twin Towers that day after running in full gear through the Brooklyn-Battery Tunnel to get to the scene -- was so inspiring that it persuaded Quesada, 23, to retrace Siller's steps.
"It takes a toll on you," Quesada said of the gear. "I was running to get through."
Along with 25 other members of the Mastic Fire Department, Quesada participated in the annual Stephen Siller Tunnel to Towers Run, which attracted 25,000 total participants, organizers said.
The event commemorates the efforts of Siller, who was on his way home to Staten Island after a shift at his Park Slope firehouse when he learned of the terrorist attacks. He couldn't drive through the tunnel, so Siller, who grew up in Rockville Centre, threw on his firefighting gear and started running.
After a fire engine picked him up about three-quarters of the way through the tunnel, Siller, 34, was killed later when the towers collapsed. He left behind his wife and five children.
Now in its 11th year, the run raises money for the foundation that Siller's family started after his death. It supports burn victims, wounded soldiers and disadvantaged children.
Thousands of Long Islanders participated, according to organizers. Sunday's runners included 50 Suffolk police officers, 10 firefighters from Holbrook and several members of the Dowling College men's basketball and lacrosse teams.
While not all had a direct connection to Siller, the event is still personal for many because they knew first responders who perished in the 9/11 attacks.
"I remember sitting in the fire department waiting for my dad to come back," Quesada said, whose father, a former Mastic fire chief, responded to the attack on 9/11 and survived.
His brother Brian Dwyer, 44, of Miller Place, ran Sunday in his memory.
Dwyer, a Suffolk police officer, met his colleagues at 6 a.m. in Rocky Point Sunday morning for the ride to Red Hook. The early wake-up time, he said, was not a tough sell.
"We fill the bus in seconds," Dwyer said. "A lot of people lost friends that day."
Mary Siller Scullin, 64, one of Siller's siblings, attributed the popularity of the race to the resonance of her brother's actions on Sept. 11.
"Stephen's story is compelling and universal," she said. "It's about our need for recognizing the incredible human spirit that we have."