"The man now assisting police remains in custody", police said on Monday.
The man turned himself in to a regional West Australian police station Sunday morning, but no charges have been filed and police didn't disclose the identity of the victims or their relationship to the man.
Police said the man was in custody and assisting police with their inquiries into the case.
The dead include women and children.
"Sadly at that location, police have located the bodies of a number of deceased people including women and children", Assistant Commissioner Steel said.
He said specialist forensic police would investigate the scene, which was stil at a "very early stage".
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"It is a tragic thing when incidents like this occur", said an assistant commissioner, Paul Steel.
A neighbour, who only wanted to be known as Alfie, said police arrived at the home on Sunday banging on back doors and jumping fences.
Police then went to the Bedford home where they discovered the bodies about midday.
Neighbours watched on as forensic officers and homicide squad detectives descended on their quiet suburban street and started to lock down the home for further investigation. "It is safe, we have grown up all our lives and this is just so sad and horrific".
"This is a tragic event and will have an impact on family and friends, the community, and the emergency services who first responded to the tragic scene".
It is yet to be determined how long the bodies had been there, Mr Steel added. "They just looked like a normal family".
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Other neighbours spoke of a community that was close, calm and peaceful.
"It is a awful, bad tragedy for the family", he said. "I'm deeply saddened by what's happened".
It has taken everyone by surprise, we are all in complete shock.
In July, Kiwi mum Michelle Peterson, 48, and her children Bella, 15 and Rua, 8, were killed in the suburb of Ellenbrook.
The home is still sealed off with police tape, and investigations are still ongoing.
Peter Miles, 61, his 58-year-old wife Cynda, their daughter Katrina, 35, and her four children - daughter Taye, 13, and sons Rylan, 12, Arye, 10, and Kadyn, eight - were found dead at their Forever Dreaming Farm in Osmington on May 11.
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