The bodies of a woman aged in her 40s and two young children were found in a burnt-out car in Coogee in Perth's southern suburbs on Monday, police have revealed.
WA Police said the woman and children, an eight-year-old boy and a 10-year-old girl, were believed to be from the same family.
The bodies were found in the vehicle in a car park at John Graham Reserve.
Major Crime Division Detective Inspector Quentin Flatman said it did not appear anybody else was involved in the deaths.
He said police had not ruled it out but it was "very unlikely", with the fire believed to have been started inside the vehicle.
Inspector Flatman said investigations were ongoing and "all avenues" were being explored.
"What I can say is that at this point, it does not appear that there is any third-party involvement in this event," he said.
"There is no need for anyone to be concerned within the community as to any other person being at large or walking around the community."
Children's father returning to Perth
The Department of Fire and Emergency Services was called to the reserve just after 12pm on Monday.
Police initially said "at least one person" had been discovered dead inside the car.
Inspector Flatman said the children's father had flown out of Perth on Sunday night, but was now on his way back to Perth.
"Very sadly the father departed Perth on a planned scheduled trip to see other extended family overseas. We had some difficulty contacting him,” he said.
"One of the officers from the Homicide Squad had the unfortunate task of advising him overseas via telephone what had occurred.
"He is currently on an aircraft coming home."
No evidence of firearms being used: police
Inspector Flatman said had been reports of gunshots from the scene, but he believed they were sounds from the vehicle fire.
"When a fire impacts upon a vehicle, there are some noises that are made, that maybe [people] construed with being gunshots," he said.
"At our very, very early preliminary investigations, it does not appear to be anything connected to any firearms.
"We suspect … that the popping or that the gunshot sounds that were heard was the fire consuming the motor vehicle itself."
Anyone who was in the area at the time or who has information has been urged to contact investigators.