A woman died in a house fire on Long Island Saturday night, police said.

Suffolk County homicide and arson detectives were investigating the fire, which broke out in a home on Myrtle Avenue in West Islip at just before 8 p.m., a spokesperson told The Post.

But the preliminary investigation determined the fire wasn’t criminal in nature, a news release from Suffolk cops said.

The adult female, who was alone in the house, was not identified.

The Suffolk County Medical Examiner will determine the woman’s identity, according to cops.