Stephanie and Ben are thought to have suffered cardiac arrests
A fire that claimed the lives of a brother and sister in Devon on Saturday is believed to have been an accident.
Eight-year-old Ben McAuliffe and Stephanie Wojak, 15, died in hospital after being rescued from their home in Ellacombe Church Road, Torquay.
Neighbours helped to rescue parents Michael and Gill Wojak and Ben and Stephanie's 20-year-old brother Ricky.
Investigators have ruled out arson, but are trying to find out how the fire started and why it spread so quickly.
Insp Glen Mayhew from Devon and Cornwall Police said it was being treated as a "tragic accident".
It is thought Stephanie and her foster-brother suffered cardiac arrests as a result of smoke inhalation.
The area remains cordoned off, but floral tributes have been left outside the family's badly damaged home.
All the family's photographs and personal belongings were destroyed by the fire.
Stephanie was a pupil at Westlands School in Torquay and head teacher Mike Stewart described the teenager as a "delightful girl who was liked by everyone."
The fire service said no smoke alarms sounded in the house
Stephanie's brother Ben, who was autistic and had learning difficulties, was fostered by Michael and Gill Wojak when he was a baby. Ben and Stephanie were referred to as brother and sister.
Ben attended Combe Pafford special school. His natural parents, who also live in Torquay, had been told of his death.
Mr Stewart said he had spoken to Ben's head teacher, who described him as a "well-liked lad who was doing well".
"Mr and Mrs Wojak were very supportive parents and they took an active interest in the school and the education of their children, my heart goes out to them," he said.
"I have heard about the courageous attempts to save lives by people in this community, it is obviously a community that cares for one another and Stephanie typified that care.
"How do you cope with grief like this? These are the incidents that you never want to face as an educationalist."
Emergency services were alerted at about 1030 BST on Saturday and eyewitnesses reported the windows of the house being blown out and a black pillar of smoke filling the sky.
Neighbours battled through fierce flames and thick smoke to rescue Mr and Mrs Wojak from an upstairs rear bedroom.
One climbed on to the roof of the house to pull Mrs Wojak out of a window while another man used a ladder to get inside the property and drag Mr Wojak out.
The two men, who have been hailed as heroes, will be nominated for police and fire bravery awards.
Another neighbour, 23-year-old Ben Long, who lives opposite the Wojak's house said: "It was one of the worst things I have ever seen - we could just stand by watching helplessly.
"It is not like any fire that I have ever seen, it was so intense and you could feel the heat from inside our house."
Mr and Mrs Wojak and their eldest son were treated in hospital for the effects of breathing in smoke. They have since been released.
Insp Glen Mayhew talks about the heroic efforts of neighbours trying to save family members from the fire