Police believe a Victorian mother killed her three children before taking her own life after the four were found dead in a north-west Melbourne home.
Multiple media outlets have identified the victims of Thursday's tragedy in Tullamarine as Katie Perinovic, 42, and her children Claire and Anna, aged seven and five, and three-year-old Matthew.
Tomislav Perinovic, 48, believed to be the woman's husband and children's father, called emergency services to report the deaths about 12.20pm on Thursday.
He assisted police and has been released without charge, a Victoria Police spokewoman said on Friday.
She said detectives had also spoken with other family members, friends and neighbours of the deceased, with a report to be prepared for the coroner.
"Homicide Squad investigators have formed the preliminary view that the 42-year-old woman is responsible for all four deaths," the spokeswoman said in a statement.
Acting Deputy Commissioner Robert Hill said police would continue to support the families of those involved over the coming weeks.
"I know there will be many people in the community struggling to understand and come to terms with this tragedy," he said.
"This has also been an incredibly difficult time for both the police and paramedics who responded and attended the scene yesterday."
"This has been an incredibly heart-wrenching experience for all concerned."
Grieving locals began leaving flowers outside the home on Friday morning, as crime scene cleaners later filtered in and out of the property.
A young girl and her mother came to leave flowers and a note.
Neighbours of the family were shaken by the incident.
"I used to see the children, they used to play in the cubby house at the back. It's really sad," one told reporters.
Another said: "They were beautiful, a lovely family. This is going to be felt for a very, very long time - not just the adults but the kids. The kids are really going to feel this."
Neighbour Marie Groves told the ABC the family attended her daughter's birthday party last year.
"It's so close to home, these are people who've spent time in my home, my kids love their kids," Ms Groves said.
"How am I going to tell my kids?"
She said Ms Perinovic was a physiotherapist who had only recently returned to work after taking time off to care for Matthew.
According to the Herald Sun, Ms Perinovic left the clinic "unexpectedly" three months ago.
Acting Assistant Commissioner Mark Galliott earlier said the situation was "difficult to comprehend".
"This will have long-lasting effects on the police that attended, on extended family, the community, the neighbourhood, the emergency services and everybody else involved," he said.
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Australian Associated Press