A mother and her three children found dead at a property in Melbourne's northwest have been identified.
The bodies of 42-year-old Katie Perinovic, her two girls Claire, 7, Anna, 5, and three-year-old son Matthew were found inside the home on Thursday afternoon.
Her husband, Tomislav Perinovic, 48, was also at the Tullamarine site on Burgess Street, police said.
"We understand the three children were siblings. We also understand the three children were that of the female that was found deceased," Acting Deputy Commissioner Robert Hill told reporters.
"We also understand the male was the husband of the deceased female, and the father of the three children."
"It's very important we do not speculate. The circumstance of this event are yet to be determined.
"We cannot afford to make any assumptions as to what occurred."
Hill said police would work through the crime scene methodically and the man had provided police with his account of what happened.
"It is a tragic event to lose life, in any circumstances," he said.
"But when it involves three children — the second event this week where we've seen the loss of children in horrific circumstances — it does impact upon the community."
Acting Assistant Commissioner Mark Galliott said police would remain at the scene all night.
"The loss of young lives in circumstances such as this is are difficult to comprehend," he said.
"This will have long-lasting effects on the police that have attended, on extended family, the community, the neighbourhood, the emergency services, and everybody else involved.
"They'll be lifelong memories that they'll have to deal with."
Galliott said information indicated the man was not injured.