New Jersey Police Department carry an American flag at the memorial observances on the 13th anniversary of the September 11 terror attacks.(Associated Press)
The Fire Department of New York (FDNY) says three retired firefighters who worked at ground zero have died on the same day from illnesses related to the September 11, 2001 attacks.
Lt. Howard Bischoff and firefighters Robert Leaver and Daniel Heglund died on Monday.
Fire Commissioner Daniel Nigro says their deaths are "a painful reminder that 13 years later we continue to pay a terrible price for the department's heroic efforts."
The three worked at the World Trade Center site after the attacks. One had leukemia, one had esophageal cancer and a third had colon cancer.
The Uniformed Fire Officers Association says first responders showed health problems soon after the attacks, with 99 percent of exposed firefighters reporting at least one new respiratory illness.
The FDNY lost 343 firefighters on September 11.