Quebec police say the cause of a house fire in Thurso, Que., that killed two young girls was likely an electrical problem.

The provincial police, Sûreté du Québec, are looking at whether the fire started in the basement in the electrical junction box. They have ruled out any criminal intent.

Two sisters, aged three and eight, were found dead in the house in Thurso, about 45 kilometres east of Gatineau, after the Wednesday morning fire. Their parents, three of their siblings and a child who was staying overnight at the home all managed to escape.

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Anouck Robineau, 11, survived a fire in Thurso, Que., that killed two girls, 3 and 8. (CBC)

The parents, Martin Leger and Natashas Fortin, and a daughter, 12, remain in hospital. Fortin is in hospital as a precaution after being slightly injured.

Doctors say the girl is in critical but stable condition after being badly injured. Leger was also critically injured but has improved enough to be moved out of intensive care.

A makeshift memorial outside the house is continuing to grow as local residents show their support for the family.

Eleven-year-old Anouck Robineau said she was scared for her life when she escaped from the home with her friend, the girl who is now in hospital fighting for her life.

Anouck said she was on a sleepover in the basement of the two-storey house on Lacroix Street when they heard screams. Her friend tried to open the door to go upstairs but was enveloped by flames.

Anouck said she grabbed her friend and pulled her back downstairs before closing the door. The girls then tried to escape through a basement window, but the first two were covered by metal bars.

They managed to escape out of a third window not covered by bars, because it had been kicked in by her friend's father, who was outside.

8-year-old victim tried to escape

Once outside, the pair were on the sidewalk when they, her friend's parents and three other children, including a six-month-old baby, looked up to see an eight-year-old girl trying to escape out of her bedroom window on the second floor.

Anouck, who has a gauze bandage on her wrist to cover burns suffered while trying to escape, said she saw flames surround the girl, who could not open the window. The father tried to climb up to rescue the girl and her three-year-old sister, but he couldn't reach them.

Firefighters found the bodies of the girls inside the home several hours later.

The children who escaped the fire, went to the home of neighbour Sylvain Leblanc where paramedics began initial treatment. Leblanc had described them as being in "bad, bad shape."

On Wednesday, Leblanc recalled waking up at about 4:30 a.m. to the sound of a woman screaming and saw flames coming from the home.

Firefighters battled the fire for more than three hours before they could finally enter and search the home.

Fire officials don't know if there were any working smoke detectors in the home.

The family had moved into the home about a year ago.