NEW YORK (CBSNewYork) — A beloved FDNY hero has lost his battle with cancer.

Ray Pfeifer was one of the thousands of firefighters who worked for months on the toxic pile at ground zero following the attacks of Sept. 11, 2001. Six years later, he was diagnosed with renal cancer.

READ MORE: NYC Hospitality Alliance: Mayor De Blasio 'Grinch' For Vaccine Mandate That May Keep Tourists With Young Children Away

READ MORE: Amazon Web Services Reports Major Outage; Netflix, Venmo, Instacart Among Many Affected Sites

While battling cancer, Pfeifer championed the Zadroga Bill, which secured health care for 100,000 people.

Fire Commissioner Daniel Nigro said, “The entire FDNY family deeply mourns his loss.”

MORE NEWS: Strong Winds Topple Jersey City Home Under Construction; 'Devastated' Neighbors Left Homeless: 'It's A Disaster Right Now'

Pfeifer was 59 years old.