Heavy flames shot through the home on Depot Road just before 11:30 p.m.
A 911 caller reported a fire at the location.
Five fire departments responded to extinguish the blaze.
Barry Garfman, 82, was pronounced dead at the scene.
His son, Dustin Garfman, 42, also a resident, was transported to Huntington Hospital before being transferred to Stony Brook University Hospital in serious condition.
The cause of the fire is still under investigation, but officials say it does not appear to be criminal in nature at this time.
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