(CNN) They were father and son. They were first responders on September 11, 2001, and now, their recent deaths are being tied to their heroism on that horrific day, more than 15 years later.

Robert Alexander, 43, died this week of cancer related to his service at the World Trade Center site after the 9/11 attacks, according to a statement released Wednesday by the Uniformed Firefighters Association.

His death follows that of his father, Raymond Alexander, who about nine months ago died of cancers also tied to ground zero, said Ginger Alexander.

Ginger, the mother of Robert and wife of Raymond, spoke proudly of the men in her family, pointing out that “Robert is a third-generation fireman. His grandfather, his father and him — 80 years (of service) all together.

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