The twin girls, two years old, another three-and-a-half-year-old girl, her mother and grandmother are the victims of what is feared to be the third mass murder in Western Australia this year.
The ages of the children and their relationship with the two adult women found in a Bedford house in East Perth were confirmed Monday by the WA police.
"It's kind of tragic when incidents like this happen, it sends a ripple effect in the Western Australian community," said Assistant Commissioner of the Metropolitan Region, Paul Steel.
The shocking discovery comes after the shooting deaths of three adults and four children in Osmington in WA regional in May and the death of a mother and her daughter, aged 15, and son, eight, in Ellenbrook, in the northeast of Perth, in July.
A man in his 20s turned himself over to a regional police station on Sunday, before the police went to the house where they discovered the bodies around noon.
It is believed that the man was known by women and children, although the police have not confirmed it.
"The man who currently helps the police remains in custody, no charges have been filed at this time," police said in a statement Monday.
The police have not said how and when the women and children died.
The homicide detectives and the specialized forensic police will continue Monday exploring the Coode Street home in search of evidence and clues about what happened after the shocking discovery.
"Depending on the size of the crime scene it will take a period of time, and it could be a number of days," Steel said.
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