'We're in limbo': agonising wait for sons of woman missing in fire

Jason Kuyltjes and his two brothers have been left in limbo after a horror blaze ripped through the unit his mother Patricia Kerr was staying at on Railway Street, Teralba in the early hours of the morning.

It could be days before they have any answers about what happened to their mum, Mr Kuyltjes said, telling the Newcastle Herald police have been unable to enter the property due to structural damage.

"That's the killer, no one will tell us if anyone is in there," he said.

"Surely someone can stick a head in, even if we're taking forensic evidence, surely we can look inside the house.

"That's been the worst part, your mind just goes in circles, we're in limbo at the moment and we don't know what to do."

Mr Kuyltjes said his mother, a Newcastle local, was visiting a friend at the apartment at the time of the fire.

According to Mr Kuyltjes, the family has been told it could be two to three days before police are able to enter the apartment to search for his mother.

He said that his mum's car was located outside the home with her phone inside.

"I can't even tell you if we are looking for someone or not, they don't know," Mr Kuyltjes said.

His voice broke as he described her as a woman with "a million friends", a free-spirit who "wouldn't take shit from anyone".

"Everyone knew her, she was wild to be honest," he said.

"She made me more grounded because of how wild she was, a million personalities in one, anyone who knows her would understand."

About 50 firefighters rushed to the scene after emergency services received multiple calls about the blaze just before 4.15am on Thursday.

When they arrived, the two-storey townhouse had already suffered extensive damage and firefighters quickly jumped into action, some battling the blaze while others rushed into the burning building in a search and rescue effort.

Fire and Rescue NSW Acting Superintendent Mathew Sigmund told the Newcastle Herald this morning that when crews arrived they were confronted by "extreme fire".

"They did get up to level two, but unfortunately due to internal structural collapse they had to withdraw," he said.

Firefighters have worked alongside Lake Macquarie Police District officers to try to locate the two unaccounted for residents as it is uncertain whether they were home at the time.

An adjoining townhouse was also damaged by the blaze, but a NSW Police spokesman confirmed all other impacted residents had been safely evacuated.

Police have launched an investigation into the cause of the fire, which is still unknown.