He would spend the next eight months scouring through the rubble, "searching for friends," he said.
But this weekend, he would pay the ultimate price for his heroism. After an 8-year battle, Pfeifer died of terminal cancer, caused by the noxious cloud that hung over the disaster site.
For tens of thousands of people, Pfeifer's legacy lives on through the Zadroga Bill
, which secured medical care for 9/11 first responders, survivors, and recovery workers.
New York City Mayor Bill de Blasio honored Pfeifer
with a key to New York City last year, "for his work to pass the Zadroga Bill," the mayor's office said in a tweet.
Today, de Blasio tweeted a message of condolence. "With the death of Ray Pfeifer, New York City has lost a hero and an inspiration. My prayers are with his family and all of the FDNY."
"We got something done that I never would have thought would have gotten done," Pfeifer said.
"We dealt with people who didn't really get it. We held it to (politicians) about never forgetting. We told them, 'We're still dying from terrorists. We're still sick from terrorists.' They started to get it," Pfeifer said.
"I was just the poster boy ... but everybody did something," he said.
In December 2015, Congress passed the Zadroga Act extension, which extends the health program coverage to 2090.
More than 33,000 first responders and survivors are living with illnesses or injuries related to the attack, according to a release by Congress following the extension.
'A true fighter'
Pfeifer was diagnosed with stage 4 cancer that was linked to his work at ground zero.
He spent his final days in hospice care, suffering from brain cancer, and cancer in his nodules, lungs and adrenal glands, according to CNN affiliate WPIX.
New York Sen. Chuck Schumer reacted to the news of Pfeifer's parting on Twitter, "Just learned that Ray Pfeifer has died. You meet very few truly great men in your life. Ray was one of them."
"Ray Pfeifer was a true fighter who bravely battled fires as a New York City Firefighter and fought tirelessly for all first responders who -- like him -- suffered from World Trade Center-related illness. The entire FDNY family deeply mourns his loss," said Fire Commissioner Daniel A. Nigro in a statement on Twitter.
Because of Pfeifer's leadership, de Blasio said, survivors "get to wake up in the morning and not have that horrible, pervasive worry about their future. They don't have to wonder what's going to happen next to them and their families because they did the right thing when it was their moment to stand up."
Pfeifer leaves behind a wife, a daughter, and a son who chose to follow in his father's footsteps as a member of an FDNY EMS station.