The victim is identified as 61-year-old Suzanne Minervini, who lived in the home.
The flames broke out around 10 a.m. Friday at a home on Udall Road in West Islip.
Firefighters and police were quickly on the scene and extinguished the blaze, but Minervini, who was trapped inside, was pronounced dead at the scene.
Neighbors say they saw the woman's husband was panic-stricken and trying to get inside. He was apparently out when the fire began.
"He looked frantic," neighbor Kim Mastrandrea said. "And I came out, and the cops were here in two seconds. Otherwise I would've done something. But they were literally here in two seconds."
A firefighter also suffered minor injuries.
"Obviously it's not something we ever want to come across," West Islip Assistant Fire Chief Robert Celeste said. "But luckily, we do have each other, and at the same time, we have resources needed if need be."
Suffolk County Police Homicide Squad and Arson Section detectives are investigating.
Authorities say the fire does not appear suspicious, but the cause remains under investigation.
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