TWO young girls have tragically died in a house fire in the north of Tasmania in what was meant to be a fun sleepout on the Queen's' Birthday Weekend.

The sisters, Ruby Brewer, 13 and Shanzel Brewer 10, were found dead after a suspected electrical fault caused a fire at a property in Austins Rd, Turners Marsh, 30 kilometres north of Launceston on Sunday.

Ruby Brewer, 13, left, was having a sleep out with her younger sister Shanzel Brewer, 10, right. Both were killed when a fire ripped through the building. Facebook

The father of the two girls called Tasmania Police and the Tasmania Fire Service about 3am when a granny flat the girls were sleeping in out the back of the main house caught fire.

Fire investigators on site at Turners Marsh. Picture: Nick Clark

He told emergency services that his two daughters were unaccounted for.

Detective Inspector John King said it was believed the fire started from a 15-20 metre electrical cord which linked the house and granny flat.

"Crews arrived and found the granny flat was fully alight," he said.

"They subsequently extinguished the blaze, tragically a 10-year-old girl and a 13-year-old girl have lost their lives in that fire.'

'Preliminary fire scene investigations believe the cause may have been an electrical fault on an electrical cord leading out to the granny flat.'

"An extension cord and an electrical heater in the flat are forming a major part of the investigation.'

He said initial information was there was not a smoke alarm in the flat.

Det-Insp King said three other children, under the age of five, were in the rented house at the time.

The two girls slept from time to time in the granny flat, he said.

He said the girl's parents were absolutely devastated.

The deaths have shocked the hamlet of Turners Marsh, which is situated about seven kilometres from the town of Lilydale. Lilydale has a population of less than 1000 and Turners Marsh, significantly less.

It is remarkable only for its bushland with some small farms and a carting track.

A small bouquet of flowers was propped up beside the property's letter box yesterday afternoon.

It is understood the girls attended Lilydale District School and on social media yesterday, rriends and family expressed their grief.

"Waking up to hear this tragic news and still can't believe my two beautiful little cousins have been taken away from us," Kelsey Lee wrote on Facebook.

Miraki Thompson wrote: "My heart is broken I feel so lost! No words can explain the pain!"

"RIP girls I honestly don't know what to say or do."

The girls were described as having loving hearts.

"'All that met them fell in love straight away, their smiles would just melt your heart," Sharnie Bosworth said.

"Both these young ladies ... had such promising futures, they were intelligent and clued on young ladies that will be greatly missed by so many especially their loving family."

"So today we all must say our goodbyes to two beautiful girls, but now in great sorrow we gain two of the most beautiful angels to watch upon us."

Ms Bosworth has also created a Go Fund Me page to assist the family with the cost of the funerals.