NEW YORK (NBC) -- A New York City firefighter who was a 9/11 responder died Monday after he was rushed to the hospital in cardiac arrest from the scene of a warehouse fire.
A 17-year veteran of the force, Lt. Richard Nappi was overcome by heat and collapsed while battling the blaze.
It was the FDNY's first line-of-duty death in nearly three years.
At the hospital, Mayor Bloomberg comforted Nappi's widow, Mary Anne, his 12-year-old daughter, Catherine and his 11-year-old son, Nicholas, saluting the sacrifice their loved one made keeping the city safe.
"It's very tragic. There's nothing we can ever say," Bloomberg said. "They were in love, lived together, had kids. All of a sudden, he's gone."
Nappi, a 47-year-old native of the Bronx who lived on Long Island, was a responding firefighter on 9/11.
The mayor said Nappi "helped rebuild our city in ways New Yorkers understand."
Fire Commissioner Salvatore Cassano, who worked with Nappi while he was assigned to Engine 7 in lower Manhattan, called him "a leader that people would follow."
Before joining the FDNY Nappi was a parole officer and a case worker for Suffolk County's Department of Social Services.
In addition to his work with the FDNY Nappi also served as a volunteer firefighter and deputy chief instructor with the Suffolk County Fire Academy in Yaphank.
"Rich was a character. He was a very outgoing, bubbly type of person," said Chief Bob Hopkins, who worked with Nappi at the Yaphank training center.
It's not clear what cause Nappi to suffer a heart attack but officials suggested the uncharacteristically hot April day was a contributing factor.
"When the firefighters are wearing bunker gear, they're encapsulated. It's very warm," said FDNY Chief Medical Officer Kerry Kelly. "When you add the ambient temperature being so hot, it adds to the burden on an individual."
Seven other firefighters were injured battling the fire, which broke out in a warehouse in Bushwick at about 1 p.m., authorities said.
A large pile of cardboard boxes reportedly caught fire on the second floor of the two-story warehouse.
The fire was brought under control just before 4 p.m.
More than 150 firefighters worked on the blaze.
The cause of the fire was not immediately known.