A family who fled Afghanistan as refugees has been struck by tragedy after two of their "sweet" daughters died when smoke filled their Geelong bedroom.
The toddlers' parents woke to find the front room of their Loch Street, East Geelong home full of smoke just after 8am on Thursday.
Detective Senior Sergeant Mark Guthrie says it appears a toy fell on an electric bar heater in the room where the girls, aged two and three, were sleeping.
It's not known how long the fire was smouldering before it was discovered.
The family had fled Afghanistan, travelling first to Iran, before coming to Australia several years ago.
The girls' father rushed to the home of neighbour Charlie Corke, a doctor and friend, for assistance.
Dr Corke told AAP he wasn't home but another refugee family staying with him had helped.
The parents drove the girls to hospital where they were pronounced dead. It's believed they died as a result of smoke inhalation.
Their six-month-old sister, who was in another room, was treated for smoke inhalation. Neither she nor her parents were injured.
Dr Corke visited the family in hospital on Thursday morning and said they were understandably devastated.
"It's everybody's worst nightmare," he said.
"They're a lovely family. They're well liked and I hope there'll be adequate support in the community."
Det Sen Sgt Guthrie told AAP it was a tragic set of circumstances.
"They're deeply traumatised by the whole lot," he said.
One neighbour said the "sweet" girls would stop on their way past to pat her dog.
"They were smitten," she said of the parents, who have lived in the street three or four years.
"You could see in their eyes they really loved their children."
Another neighbour said she knew the family well and the "beautiful, very happy, cheerful little girls" had played in her backyard.
Arson investigators have been investigating the cause but it's not believed to be suspicious.
They removed a bar heater and its box from the home.
From the outside of the house, there's no indication of the tragedy that unfolded.
Det Sen Sgt Guthrie said there was a lot of smoke damage inside the home but it was contained to one room.
He urged people to take care around heaters and make sure nothing comes into contact with them.
The incident has taken a toll on those who attended.
"It's probably some of the worst scenes you'll go to when there's children involved," Det Sen Sgt Guthrie said.