A family has lost everything after their Spofforth Street home went up in flames.

A 17-year-old girl was looking after her three siblings, including a toddler, when a smoke alarm went off in the hallway of their home just after 5pm.

Next door neighbour Victor Coussens said he arrived home "about five minutes after the fire came".

"There was a hell of a lot of smoke," he said.

"You could see the flames through the broken windows, and there were fire trucks and police trucks all over the street.

"We parked at the end of the road and walked up, (because) we couldn't get in."

The children raced to a bedroom at the rear of the fibro NSW Housing property to find a mattress well alight.

A single mother, four children and two dogs reside at the house.

No one was injured, however the home was completely destroyed in the fire.

The children's parent, who was reportedly in Sydney at the time of the incident, was notified.

Mr Coussens said he spoke to the family in the immediate aftermath of the incident, and praised the efforts of the teenage daughter.

"The smoke alarm went off, she saw the fire in the mother's bedroom... By the time the smoke alarm went off and she opened the door, the mattress was on fire.

"So the first thing she did was grab the kids and get them out of the house, grab the pets and took them out, and then called 000.

"For a teenager, she did brilliantly. She did everything right."

Mr Coussens said residents of the typically quiet street were still a little shocked.

"You see those things on TV and you read about them, but it's always somewhere else," he said.

"You never expect to see it happen next door to you."

Mr Coussens estimated that the family affected had been living there for between six and 12 months.

Another next door neighbour, Hayley Gatehouse said she arrived home just as the incident occurred.

"I saw smoke, and windows exploding, and the fire spreading everywhere," she said. "There were so many explosions. It's destroyed everything.

"It's devastating... They lost everything. Luckily they all got out before it exploded."

Ms Gatehouse said as of Monday morning that the affected family hadn't returned to visit the home.

Regarding the potential cause of the blaze, Fire and Rescue NSW duty commander Illawarra, Inspector Chad Wallace said the matter had been handed over to the police forensic team.

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