Photo: Police close the street outside the Bedford home. (ABC News: Eliza Laschon)
Photo: The Miles family (rear) Katrina Miles, Peter Miles and Cynda Miles, and children (front) Rylan, Kayden, Taye and Ayre at a family wedding. (Facebook: Katrina Miles)
Multiple bodies were found at a home in Coode Street in Bedford after a man went to a regional West Australian police station on Sunday morning.
That man, believed to be in his 20s, is now in custody but no charges had been laid by Sunday evening.
Police would not confirm exactly how many people had died, but Assistant Police Commissioner Paul Steel said there were "up to" five bodies.
The exact ages and genders of the victims are unknown but at least one of them was a woman, police said.
The relationship of the victims to the man in custody is also unknown.
Assistant Commissioner Steel said there were "no ongoing safety concerns" at the scene.
Neighbour said house had been quiet all week
Locals said a young family lived at the house, with an older woman visiting regularly.
Coode Street resident Richard Fairbrother, who lives next door to the house where the bodies were found, said he last saw the family more than a week previously, as he had been away.
"We've just been on a holiday and come back yesterday (Saturday) to silence in the street," he said.
"We noticed that the house next door was pretty quiet, which was unusual, being that they had the young kids.
"We had some friends staying here who have also mentioned that they didn't see or hear anybody next door for the week that we were away."
Mr Fairbrother said it was common to see the children playing around the house.
"We had mentioned to our friends that were staying that there was likely to be some noise from the kids next door, and they were a little surprised that there wasn't noise from the kids next door," he said.
"We'd been around to their house once or twice, and vice versa. It's just terrible to hear, terrible.
"We weren't that close, [but] we could hear and see the kids playing in the backyard quite often."
Neighbour Vagner de Souza said he regularly saw a family outside the house where the bodies were found.
"Just a normal family, you would never imagine anything like that happening," he said.
"You hear something happening so close, it's really distressing."
Maria Manfredini, a long-term resident in the area, described the incident as "tragic on every level".
"It's horrid to think that in such a beautiful area, that's calm and so quiet, that something so tragic has taken place," she said.
"We're all in complete shock."
Police trying to piece together timeline
Assistant Commissioner Steel said the investigation was still at a "very early stage", but described the incident as a tragic event.
"It is tragic not only for the family and the friends, it is also tragic for those first responders who are forced to attend such scenes," he said.
"It does send a ripple through the community of Western Australia."
Assistant Commissioner Steel said officers were still working to determine the timeline of what happened.
"We are three hours into this investigation, I have no further detail in relation to those who are present at the location," he said.
Police have blocked off traffic around the home and forensic officers are onsite.
Homicide detectives are leading the investigation.
Latest in a string of WA mass killings
It is the third time this year that WA Police have been confronted by what appears to be a mass murder crime scene.
In May, seven people were found dead after a mass shooting in a house in Osmington, near the tourist town of Margaret River in WA's South West.
Katrina Miles and her four children were found shot dead in their beds, and the body of her mother Cynda Miles was found in an adjoining property with gunshot wounds.
The children's grandfather, Peter Miles, was also found dead from a gunshot and three firearms belonging to him were found on the property.
It was the worst mass shooting in Australia since the Port Arthur massacre in 1996, when 35 people were shot dead in Tasmania.
Then in July, a mother and two children were found dead in a house in Ellenbrook, in Perth's north.
The woman's son, Teancum Vernon Petersen-Crofts, alerted authorities to the crime after entering a nearby convenience store, where staff called police.
When officers went to the house, they found Michelle Petersen and her son, Rua, dead, and her daughter Bella in a critical condition.
She later died on the way to hospital.
Mr Petersen-Crofts has been charged with three counts of murder and remanded to the secure wing of Graylands Hospital while he awaits his next court appearance.