This article deals with suicide and family violence and might be triggering for some readers.
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 spokeswoman 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.