Two of three children who were found unconscious in their burning home have died almost three days after being rushed to hospital.
Emergency services were called to the brick property in Sydenham, in Melbourne's northwest, on Sunday night to find smoke and flames billowing from the roof.
It took fire crews up to 30 minutes to retrieve the siblings - two girls aged five and one, and a boy aged three - before they were taken with critical injuries to the Royal Children's Hospital.
Police said the two girls died surrounded by family in hospital on Wednesday morning, while the boy remains in a critical condition.
Detectives from the arson and explosives squad are investigating the fire, including who was in the property at the time and just before the blaze.
The father of the boy told reporters on Tuesday the three children were "happy little kids" and must have felt "petrified" during the ordeal.