Three children have been killed in a house fire in Sydney's west, with police alleging a father barricaded them inside with four other children.
Police also allege he tried to stop emergency responders from saving them.
Neighbours raised the alarm, calling triple zero at 1am today on Freeman Street at Lalor Park.
In just six minutes, firefighters were on the ground to battle what a neighbour described as an "intense" fire.
"The flames were shooting out the front window at 20 feet," Brett said.
Two adults and seven young children were inside.
Another neighbour said she was woken by screaming.
Two boys aged three and six years old were given CPR on the street but they couldn't be saved and a 10-month-old baby girl was found dead inside the home.
As rescue crews, emergency services and locals battled powerful flames, Dean Heasman was allegedly pushing the children back in.
"We're alleging that 28-year-old man took direct actions to prevent the rescue of those young lives that were lost," NSW Police Homicide Squad Superintendent Danny Doherty said.
"We will allege that this 28-year-old man's actions were directly the cause of the death of these three young people.
"We've seen three young lives have just been taken away in the most tragic of circumstances, quite unimaginable how the family is coping with this."
A nine-year-old girl and three boys aged four, seven and 11 were taken to Westmead Hospital, where a 29-year-old woman was also treated.
Heasman was in an an induced coma this evening.
Neighbours said the surviving children told them the man ordered them to stay inside the home as it burned, one of them claiming he tried to fight in a bid to save his siblings.
"Dad tried to kill us," the child allegedly told rescuers.
Residents claimed they saw the man attempting to drag the terrified children back inside. They said he was shouting "leave me here to die".
NSW Premier Chris Minns labelled the incident "horrifying and senseless" and offered the family support.
Acting Superintendent Jason Pietruszka praised the heroic actions of officers and a neighbour who went to extraordinary measures to gain entry to the home.
"Police approached, and a neighbour," Pietruszka said.
"They then had to bring the offender under arrest, they suffered various injuries as a result and that was done so in a manner that was quite extraordinary.
"The neighbour that did try to assist helped further lives from being lost."
It's understood the man arrested at the scene was not previously known to police and had no existing apprehended violence order against him.
Fire and Rescue NSW Superintendent Adam Dewberry praised the work of first responders at the confronting scene.
"Just sitting there watching a little child sitting on a police constable's lap, or she's comforting him while paramedics are providing treatment," he said.
"Firefighters are handing out our Care Bears, our little teddy bears, to try and give them that little bit of comfort."
An investigation is underway into the circumstances behind the blaze, police said.
A report will be prepared for the coroner.
Support is available from the National Sexual Assault, Domestic Family Violence Counselling Service at 1800RESPECT (1800 737 732).
