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Ray Pfeifer, the beloved New York City firefighter who battled terminal September 11-related cancer for eight years, died Sunday, the department announced. He was 59.

The retired firefighter contracted the illness after he spent eight months at the World Trade Center site in 2001 combing through the rubble to search for survivors, according to Fox 5 NY.

"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," Fire Commissioner Daniel A. Nigro wrote on the FDNY Facebook page.

Pfeifer fought to get the Zadroga Act passed in Congress, a law that guarantees medical care for 9/11 first responders. He earned a key to New York City last year for his work and dedication.

During his last few months of his life, Pfeifer pushed to have his name and other first responders who died from 9/11-related illnesses placed on the FDNY's main Wall of Honor, according to PIX11 News. The wall contains names of 343 FDNY members who died during the 2001 terror attack.

"I feel that I’m being poisoned, and I’m dying, every single day, because of terrorism," Pfeifer told PIX11 News.

Pfeifer was vocal about his battle with cancer, often posting updates on his social media. In January, he marked 2,610 days since his diagnosis.

"The facts — 2610 day's of this f'n cancer and counting. But also 2610 day's with family and friends!!!!!! Thanks," Pfeifer wrote along with a photo.

Dozens of people, including Sen. Chuck Schumer, paid their condolences to Pfeifer.

"It was a privilege to know Ray and to work with him. My condolences to his family and all of FDNY," Schumer wrote on Twitter.

"Saddened to hear of the passing of FDNY firefighter Ray Pfeifer. His tireless advocacy was instrumental in aiding 9/11 first responders," New York Gov. Andrew Cuomo said.

Pfeifer leaves behind his wife and two children, one of which who is also a firefighter.

Click here for more from Fox 5 NY.