Mother-of-three Mara Quinn was among the victims of the Bedford mass killing.
The West Australian reports, Ms Quinns daughters, Charlotte, 3, and two-year-old twins Alice and Beatrix, along with their grandmother were found dead at the Coode Street home on Sunday.
Police arrived at the property after a man, aged in his 20s, presented himself at a regional police station.
He remains in custody and charges are yet to be laid.
It is not yet known if the man is related to the deceased.
Assistant Commissioner Paul Steel said homicide detectives are continuing their investigation into the horrific deaths.
“This is a tragic event that will have no doubt have an impact, not only on the family and friends of the deceased, but for the whole of the community, those first responders who were faced with attending a scene with multiple deceased people,” he said.
“It does send a ripple through the community of Western Australia.
“Part of the homicide squad investigation is going to try and identify the time line of all events which led to this matter. How long the bodies have been there will also form part of that timeline inquiry.”
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