From left to right, former FDNY members Michael Verzi, Robert Reynolds, Vincent Mandala and Jack McCauley.
CNN  — 

Four former members of the New York City Fire Department died over a four-day period because of 9/11-related illnesses, the FDNY announced Thursday.

“To date, 287 FDNY members have had their lives cut short by World Trade Center-related illnesses, including four retired Firefighters in just the last week alone,” the FDNY said in a press release.

“These tragic losses are grim reminders of the sacrifices the FDNY continues to make, and the extraordinary bravery displayed by the members of the Department on September 11th, and in the rescue and recovery effort that followed,” the department said.

The former FDNY members – Michael Verzi, Robert Reynolds, Vincent Mandala and Jack McCauley – all died during the end of May, the FDNY said.

Union officials said at a press conference that the deaths have been difficult on the FDNY community and that such services will likely continue as long-term illnesses affect first responders.

“It’s been a very tough week for us,” said Andrew Ansbro, president of the FDNY-Uniformed Firefighters Association. “The illnesses continue to take their toll on New York City firefighters and other first responders.”

The World Trade Center Health Program shows that exposure to the 9/11 terror attacks may have caused a range of health conditions, including acute traumatic injuries, as well as diseases of the respiratory and digestive systems. The program says those exposed to the attacks also develop cancers that include lymphoma, leukemia and myeloma.