A grandfather is suspected of gunning down six members of his own family before turning the gun on himself, at a remote farm 15km from Margaret River.
The Australian reports police are treating the incident - which is Australia's worst mass shooting in more than two decades - as a murder-suicide.
Meanwhile the ABC reports that a friend of the family has confirmed that Katrina Miles and her four children were among the seven victims.
The friend also claims that Katrina's parents, whose names are listed on the property title as Peter and Cynda Miles, also died in the incident.
Earlier yesterday, police confirmed four children and three adults had been found dead at a rural property in the area.
'Police are currently responding to what I can only describe as an horrific incident in Osmington, 20km north-east of Margaret River. It is early in this investigation,' WA Police Commissioner Chris Dawson told a police press conference on Friday morning.
'Based on what we do know, this is clearly a tragedy. At about 5.15am this morning, police were called to a rural property on the outskirts of this property at Margaret River.
'Upon arrival, police located seven persons deceased. Four children and three adults. The bodies of two adults were located outside, five bodies were located inside a building on the rural property.
'Two firearms have been located at the scene. We are trying to locate other members of the family and friends. I'm not in a position to release any further details about the identities of the deceased.’