The Darden Clarkenumber of City of New York Fire Department workers who've died from World Trade Center-related illnesses reached a morbid milestone over the weekend, equaling the number of responders killed on Sept. 11, 2001, a department official said.

FDNY Commissioner Laura Kavanagh announced the deaths of two fire department workers, EMT Hilda Vannata and retired firefighter Robert Fulco, as a result of the time they spent working in the "rescue and recovery at the World Trade Center," according to a statement posted on X, formerly known as Twitter.

Vannata died on Sept. 20 after a battle with cancer and Fulco died on Sept. 23 of pulmonary fibrosis, a chronic lung disease. Their deaths brought the number of FDNY responders that have died from illnesses related to the site to 343, the same number of FDNY workers killed on the day of the attack, according to the department.

"We have long known this day was coming, yet its reality is astounding just the same," Kavanagh said in her statement, calling it a "somber, remarkable milestone."

"Our hearts break for the families of these members, and all who love them," she added.

On the day of the attacks, thousands of first responders went to the burning towers after they were struck by commercial airliners that were hijacked by terrorists. When the towers collapsed, thousands were killed.

In the months after, an estimated 91,000 people helped in the cleanup effort, exposing themselves to toxic fumes, smoke and chemicals, according to the City of New York.

A study published last year in the Journal of the National Cancer Institute found elevated cancer risk among 69,102 rescue and recovery workers who responded to the World Trade Center, including police officers and firefighters. The most common forms of cancer identified were melanoma, thyroid, tonsil and prostate cancer.

In her statement, Kavanagh said 11,000 FDNY first responders suffer from World Trade Center-related diseases, including 3,500 who've been diagnosed with cancer.

"Our commitment to their service and sacrifice," she said, "must remain as unshakable for the next two decades as it has been for the last two."