When the smoke and flames cleared, police found a young woman dead inside.
It's not known yet whether the woman died from the fire or if the fire was intentionally set.
Police would only say the woman was 26 years old and lived at the house with three other family members.
Police did not say what caused the fire. The Suffolk County Medical Examiner is conducting an autopsy to determine the exact cause of death.
The victim's name is being withheld pending positive identification.