Story highlights All three firefighters responded to the World Trade Center on September 11, 2001

They all died of illnesses related to their time working at the site, officials say

Hundreds of firefighters and ambulance workers suffer from respiratory illnesses

Three retiree firefighters from the FDNY died this week from illnesses believed related to the September 11, 2001, terrorist attacks on the World Trade Center.

Daniel Heglund, Robert Leaver and Howard Bischoff, who suffered from cancer, died Monday within hours of each other, reported CNN affiliate NY1.

"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, New York Fire Commissioner Daniel Nigro said in a statement.

Ninety-two firefighters have died of illnesses related to the 9/11 attacks and hundreds of firefighters and ambulance workers suffer from respiratory problems, NY1 reported.

All three men rushed to the World Trade Center site on the day of the attacks. They all retired in 2003.

Photos: Photos: Remembering 9/11 Photos: Photos: Remembering 9/11 Remembering 9/11 – A group from the U.S. Navy gathers Thursday, September 11, at the Flight 93 National Memorial in Shanksville, Pennsylvania. This year marks the 13th anniversary of the September 11 terrorist attacks that killed nearly 3,000 people in New York, Washington and western Pennsylvania. Hide Caption 1 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – A woman bows her head in prayer in Shanksville, where United Airlines Flight 93 went down. Hide Caption 2 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Family members gather in the rain at the impact site in Shanksville. Hide Caption 3 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – From left, U.S. President Barack Obama, U.S. Defense Secretary Chuck Hagel and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey stand on stage as they participate in a ceremony at the Pentagon. Hide Caption 4 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Obama and Hagel bow their heads during the ceremony at the Pentagon. Hide Caption 5 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – A woman reaches out to touch a rose on one of the benches at the Pentagon Memorial. Hide Caption 6 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Tyrone McClave, of Bristol, Pennsylvania, looks up at One World Trade Center during a moment of silence in New York. Hide Caption 7 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Members of the New York Police Department, the New York Fire Department and the Port Authority Police Department carry an American flag past one of the reflecting pools during memorial observances at the World Trade Center site. Hide Caption 8 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Members of the New York Fire Department take time to reflect. Hide Caption 9 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Paola Braut, of Belgium, kisses a photograph of her son Patrice along the edge of the North Pool of the World Trade Center site. Hide Caption 10 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – A man stands across the street from the National September 11 Memorial & Museum in New York. Hide Caption 11 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Eileen Esquilin hugs her husband, Joe Irizarry, while mourning the loss of her brother, Ruben Esquilin Jr., during memorial observances in New York. Hide Caption 12 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Former New York Gov. George Pataki, left, and former New York City Mayor Rudy Guiliani were among those in attendance at the World Trade Center. Hide Caption 13 of 14 Photos: Photos: Remembering 9/11 Remembering 9/11 – Sam Pulia, the mayor of Westchester, Illinois, and a former police officer of the same town, mourns over the name of his cousin, New York firefighter Thomas Anthony Casoria, who was killed on 9/11. Hide Caption 14 of 14

Heglund was a firefighter from Rescue 4 in the Woodside section of Queens and had spent 21 years on the job, NY1 reported. Leaver was a member of Engine 202 in Red Hook and served 20 years. Bischoff was a fire officer for 19 years and served with Ladder 149 in Dyker Heights.

News of the three deaths comes as advocates seek reauthorization of a program to provide health services to people with 9/11-related health problems at least through 2015. President Barack Obama signed the James L. Zadroga 9/11 Health & Compensation Act into law in 2011.

"I'm asking [leaders in Washington] to be as brave as the people who responded on that day," FDNY Union-Uniformed Fire Officers Association President James Lemonda said at a press conference. "This is not just a firefighter issue. This is an American issue."

Government reports suggest workers at the World Trade Center were exposed to a number of chemicals that were known to be carcinogens, or agents that may cause cancer.

Cancer is plaguing a growing number of first responders and rescuers who worked at ground zero after the terrorist attack. These are cancers the federal government says are thought to be directly related to that effort -- cancers like leukemia, myeloma, thyroid and prostate cancers.

At the end of July, there were at least 1,646 certified cancer cases that have been documented by Mount Sinai Selikoff Centers for Occupational Health. There were some additional 863 cancer cases among both fire and EMS personnel, according to FDNY, which keeps a separate database for its members.