NEW YORK (CBSNewYork) — Family and friends are saying their goodbyes to three retired firefighters who died within hours of each other.

A hero’s sendoff is currently underway for firefighter Robert Leaver.

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Firefighter Daniel Heglund, Lt. Howard Bischoff, and Leaver all died Monday as a result of illnesses they came down with while working at the World Trade Center site after the attacks, according to the Uniformed Fire Officers Association.

Heglund, of the Rescue 4 unit, retired in March 2003 after 21 years with the department. Bischoff, of Ladder 149, and Leaver, of Ladder 202, retired in May 2003 after 19 years and 20 years with the department, respectively.

Heglund died just one day before his 59th birthday, CBS 2’s Jessica Schneider reported.

Services for Heglund are also being held Friday in Centerport.

Bischoff’s funeral will be held Saturday in Jackson, N.J.

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“Losing three firefighters on the same day to WTC-related illnesses is a painful reminder that, 13 years later, we continue to pay a terrible price for the Department’s heroic efforts on September 11th,” Fire Commissioner Daniel Nigro said in a statement Thursday.

NYC Resources 9/11 Health Statistics have shown that FDNY first responders showed health effects soon after the attacks, with 99 percent of exposed firefighters reporting at least one new respiratory system illness, the union said.

The FDNY has recorded more than 850 firefighters and ambulance workers with cancers that have been confirmed to be connected work at Ground Zero, the union said.

The firefighters’ names will be added to the memorial wall of FDNY members who died as a result of the attacks.

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