New South Wales Police say it is too early to tell what started a house fire that killed a five-month-old girl in Bargo, south-west of Sydney, on Sunday night.
Emergency services were called to the home on Avon Dam Road just before 6:30pm and arrived to discover it well alight.
Camden Police Area Command Duty Officer Chief Inspector Stephen Greer said the girl's grandfather was the first to notice smoke coming from the baby's room where the fire is believed to have started.
"The baby was asleep in the bassinet at the time," Chief Inspector Greer said.
"The grandparents tried to get to the child, but due to the smoke and fire they were unable to.
"The death of a five-month-old child, or any child, is absolutely tragic.
"Everybody gets affected … it's just terrible."
Four other people were in the house at the time, including an 18-month-old boy, who was taken to Campbelltown Hospital for observation.
A 79-year-old woman and a 57-year-old man were treated for smoke inhalation and lacerations, and a 27-year-old woman was treated for shock.
Chief Inspector Greer said community members did their best to help fire crews fight the blaze, which took several hours to extinguish.
"They grabbed the hoses," he said.
"They've done the best they could."
"I heard a woman calling and I looked out the window and I saw a lot of smoke," Margaret, a neighbour, said.
"The next minute I heard a pop and flames shooting out of the granny flat, so I just called it in.
"It just came up like a fireball and it just shot right through in a matter of minutes."
Another neighbour who ran across the road to try to help said he could hear screaming coming from house.
"Somebody said there was still a baby in the house; we were looking, but there was no way we were going to get in because the fire was so intense in that part of the house," he said.
"It's just not a nice thing, not when it comes to babies and all that, especially when I've got three of them.
"It just takes it from you. You worry about your own kids ... it's just horrendous to think about."
Police are investigating whether an oil heater could have been the cause of the fire.
