Mark J. Natale was a New York City police officer on Sept. 11, 2001, when two commercial jets commandeered by terrorists were flown into the World Trade Center’s Twin Towers in Manhattan.

He and his partner Michael Henry, officers in the 94th Precinct in Greenpoint, Brooklyn, helped dust-covered people fleeing Manhattan over bridges to Brooklyn and on ferries to New Jersey, then stood guard at the gates around Ground Zero in the days that followed, Henry recalled. The officers covered their faces, he said, with the masks worn by house painters. “That’s all they gave us,” he told Newsday Monday.

In the four months after the 9/11 attacks, Mark Natale also worked on and off at the embarkation point in lower Manhattan for barges moving the debris out to the Fresh Kills landfill on Staten Island, said Matthew McCauley, a retired NYPD officer who is a lawyer at Turken and Heath in Armonk. McCauley has assisted many first responders, including Natale, with their benefit claims with the September 11 Victims Compensation Fund.

On Friday, Natale succumbed to the brain cancer that had been certified as related to his exposure to Ground Zero toxins. He was 55. Natale was not ill when he retired in 2005 after 20 years on the job.

John Feal, founder of the FealGood Foundation who lobbies on behalf of 9/11 first responders and maintains a memorial at Nesconset’s 9/11 Responders Remembered Park, said more than 2,000 first responders have now died from a certified 9/11-related illness.

“The average age of the first responder was 39,” he said. “Now add all these debilitating illnesses and these men and women are getting weaker and sicker as they age.