Three firearms licensed to Peter Miles, who was found dead - along with six others - in a suspected murder-suicide near Margaret River, have been recovered at the crime scene, police say.
"Police are not searching for any other suspect", Commissioner Dawson said.
Of the seven people found at the house, five were discovered inside a converted shed, while two were found outside. The bodies of the adults were found outside of a building, while the bodies of the children were found inside. "This devastating tragedy will no doubt have a lasting impact on the families concerned, the whole community and in particular, the local communities in our south-west".
While identification of the victims is still taking place, police believe the seven dead to be adults Peter John Miles, Cynda Miles, Katrina Miles and children Taye Cockman, Rylan Cockman, Arye Cockman and Kadyn Cockman.
Mr Dawson said investigators were speaking with family members of the deceased, including the father of the four children, to try to piece together what sparked the tragic sequence of events.
"We know that other countries in response to one mass shooting have managed to craft laws that nearly eliminate mass shootings".
Their daughter, Katrina Miles, home-schooled her four autistic children in the property.More news: Chaos At Tej Pratap Yadav's Wedding, Crowds Stole Food, Crockery
Police were attempting to make contact with the victims' relatives, Mr Dawson said.
"At 5.15am yesterday morning, police received a triple 0 emergency call from a male person", Commissioner Dawson said.
"I actually spoke to him the night before the incident", said Richard Dosser, who lives about two kilometres down the road.
By Friday night, detectives had not yet formally identified those killed, only saying they all appeared to be residents at the property.
The Miles family were known in Margaret River as loving people, well liked and well respected around town.
Just last month Katrina had taken to Facebook to complain about her ex, writing: 'My ex does not stop stalking me'. That shooting led the country to strengthen its gun laws, making them some of the most comprehensive regulations in the world, as the BBC documented in 2017.
Red Cross counselling services remain available to the public at the Margaret River Community Centre, where friends have also been placing floral tributes. Instead, Western Australia authorities are referring to what may have been a domestic incident as a "mass shooting".