Firefighters say they were beaten back by flames as they tried to save a young family from an “intense” house fire in Singleton in the NSW Hunter Valley which has left three children dead.

Two five-year-old twin girls, Matilda and Scarlett Rinkin, were taken to Singleton Hospital but could not be saved and the body of their 11-year-old brother was later found inside the house.

Their 31-year-old mother and an eight-year-old girl were rescued from the house by neighbours.

The mother is being treated for burns to her back and forehead, and she and her daughter are being treated for smoke inhalation.

Police praised the efforts of the local residents for saving two lives.

“I would like to emphasise the heroic nature of the four residents in the nearby vicinity who tried to assist the people inside the house … and importantly got the mother and [daughter] out,” Superintendent Chad Gillies said.

The house in Brittliffe Close was well alight when police arrived about 3.30am, with screaming, the sound of smoke alarms and glass breaking waking neighbours.

Brock Forbes was one of many locals who were already at the house, trying to douse the blaze with hoses.

“Me and me family just woke up from a big bang and [we heard] just smashing and screaming so we ran out and grabbed the hose,” he said.

“I was trying to put the fire out and trying to save them and firefighters came and got it under control.”

Firefighters said the extreme heat from the fire forced crews into defensive mode, which meant they were forced to fight the blaze from the outside.

“Unfortunately no further internal firefighting operations could continue due to the intensity of the fire and the risk of the structure collapse,” Superintendent Joshua Turner said.

However, firefighters were able to enter the house through the windows of two bedrooms and remove two children.

Superintendent Turner said there was a combustible fireplace at the front of the house and investigations will look at whether that was a contributing factor to the blaze.

“In these winter months, heating appliances are quite prominent in fire causes,” he said.