Emergency services arrived at the scene at 3:30am where they found neighbours attempting to put out the flames with hoses, investigators said.
Due to the intensity of the blaze, fire and rescue crew were unable to continue operations inside the house and were forced to fight the fire from the outside said fire and rescue NSW superintendent Josh Turner.
Hunter Valley police superintendent Chad Gillies told media that a 31-year-old woman and an eight-year-old girl were rescued from the house and taken to hospital, where they are currently in a stable condition.
Twin five-year-old girls were taken to hospital where they were later pronounced dead, and the body of an 11-year-old boy was found inside the house. Investigations to determine the cause of the fire are ongoing.
(Production: Cordelia Hsu)