Brave neighbours pulled 31-year-old mother Kara Atkins and her eight-year-old daughter Bayley out through a window as the fire took hold, but the heat of the flames cut short their desperate attempts to continue the rescue.

Emergency services were called to Brittliffe Close about 3.30am, where they found the house in flames.

Firefighters rescued five-year-old twins Matylda and Scarlett through side windows and both were taken to Singleton Hospital, but they died as a result of their injuries.

The fourth child, 11-year-old Blake, was later found deceased inside the property.

Friends said the children's father and Ms Atkins' partner, Chris Rinkin, was working away and not home at the time of the fire.

The home is owned by the NSW government, with management switched from the Department of Family and Community Services to Compass Housing Services as part of social housing management transfer on June 4.

Fire inspectors and police combed the house on Wednesday morning, with investigations focused on a fireplace, while neighbours recalled the harrowing overnight incident.

Neighbour Braden Rodgers, along with three other people, tried to save the family as the fire ran rampant.

Mr Rodgers said his partner and a friend got Ms Atkins and Bayley out through a window, before he "kicked the door in" to go inside to try and reach the other children.

"I helped them out the window and then went through the back door, but couldn't go any further than the kitchen," he said. "I just couldn't see, even on my hands and knees, you couldn't see. We just got pushed back out the door by a heatwave, and then we just got the hoses onto it."

Mr Rodgers said the intensity of the fire could be felt 10 metres away.

"I could feel the heat it was that hot from my house," he said. "When I was standing on the lawn, it felt like i standing right next to it in the house. It was really hot."

Maria Stocks lives four doors up in nearby Tulloch Street, her home of 15 years.

Like many neighbours, she was awoken by loud screams nearby and went outside to investigate.

"The house was well lit," she said. "And poor Kara - she was just beside herself, she didn't know what to do.

"It was wailing, obviously you know when someone's in trouble - that sort of scream. It was really painful screams."

Ms Stocks said she knew a terrible situation was unfolding when neighbours, and later firefighters, were making repeated attempts to try and get inside the house.

"It was horrendously on fire," she said. "You don't run into save a dog like that, it was family. Young Braden that lived next door to Kara, he was doing his best to get into the house to try and save the other kids that were inside."

Ms Stocks said she had never seen any incident like it and felt "helpless".

"I was devastated," she said. "I just wanted to help and there was nothing anybody could do. The fire brigade and ambulances turned up, it was just one thing after another. It was something I never want to go through again."

Ms Stocks said the community would be rocked by the tragedy, particularly at King Street Public School where the children were students.

"They were lovely kids, can't fault them at all," she said, adding she did not know the family well.

"She'd take the children to school; walk past and it was just a neighbourly 'hello' - the kids would wave."

Family friend Caitlyn Stemmer set up a GoFundMe page to provide Kara, Chris and Bayley financial support.

"I can't believe it," she said. "They are a very loving family, caring and Kara has always been a good mum who would help out anyone who needed it. The kids' father Chris works away on the rail. It is just heartbreaking.

"The family will need to rebuild their lives and home, any help will be forever appreciated."

Ms Stemmer said those who knew the family were in disbelief when they woke to the news that one child had died - and then devastated as it was confirmed that three children had died.

"The twins already faced difficulties when they were born," she said.

"It is just devastating that it would happen to this family."

King Street Public School offered support to students on Wednesday and flew the school's flags at half mast.

"The school has expressed its deepest sympathy to the family and friends of the students who died in a house fire last night," a Department of Education statement said. "Counselling is being provided at the school for students and staff, and the school can assist parents in supporting their children."

Singleton mayor Sue Moore said the incident had "changed the lives of many in our community forever".

"The situation confronting those who responded to the fire on Brittliffe Close in the early hours of this morning is hard for anyone to imagine, and I pay tribute to the heroism of the neighbours who were on the scene in the first instance and the emergency services who responded," she said.

Another neighbour Shandelle Reid, 27, who was awoken by a torch at her window, said by the time she went outside the street was lined with emergency service workers and residents.

"There was the fire brigade, the police - who were actually directing people away from the live wire that was hanging from the power line," she said.

Ms Reid said the flames were "skyrocketing out of the roof" and there was a big "bang, a big explosion" when part of the house collapsed.

She described those who assisted in rescue attempts as "pretty brave, to run into a burning house".

Mr Rodgers played down his role and said he did not want any praise for his actions.

"I just did what anyone else what do and helped out," he said. "I don't want any praise, I just did it to help the family."

Hunter Valley Police District Commander Superintendent Chad Gillies thanked all those involved in the response to the tragedy.

"I would like to emphasise the heroic nature of the four residents in the nearby vicinity that tried to assist the people inside the house and importantly got the mother and the eight-year-old daughter out," he said.

Compass Housing is a not-for-profit community housing provider. Earlier this month, it took over the management of more than 1000 social housing properties in the Hunter, including 665 in Cessnock, 384 in Singleton and 27 in Dungog.

Group managing director Greg Budworth said Compass Housing was devastated by the fire and would support the family and community.

"In addition to arranging alternative accommodation for the family, Compass has conducted welfare checks on neighbours and is arranging counselling for any members of the community impacted by this tragedy. This service will be available from the Singleton Neighbourhood Centre," he said. "We are also working with the authorities and the property owner, the NSW Land and Housing Corporation, as they investigate the cause of the fire."

Newcastle Herald