Police say seven people have been found dead with gunshot wounds at a property near the town of Margaret River in Australia's southwest.
The weapons were all registered to Peter Miles, 61, and were found on his 30 acre sustainable farm in Osmington where he, along three generations of his family were found dead on Friday, police said.
Western Australia police commissioner Chris Dawson told Sky News they are not looking for any other suspects. Two other adults thought to be grandparents of the children were found dead outside the building.
The other two adults found at the scene have yet to be identified, according to the Daily Mail Australia.
Commissioner Dawson said the Margaret River community had banded together to help those affected.
They included Katrina Miles, 35, and her four children Taye, 13, Rylan, 12, Ayre, 10, and 8-year-old Kayden Cockman, along with grandmother Cynda Miles, 58 and grandfather Peter Miles.
He added: 'The loss of any life is tragic, but four children and three adults, this is a significant tragedy'.
"When Australia had a mass killing-I think it was in Tasmania-about 25 years ago, it was just so shocking the entire country said, 'Well, we're going to completely change our gun laws, ' and they did", he told comedian Marc Maron during a podcast taping.
The children's father, Aaron Cockman, was a local carpenter and builder, news.com.au reports. Police were led to the property by a phone call before dawn, Dawson said.
The unnamed relatives of the Miles family said they were "still trying to understand how this could happen".
A woman, her four children and her parents were killed in what's believed to be a murder suicide.
Augusta-Margaret River Shire president Pamela Townsend said the incident had impacted everyone in the area.
"Cynda was a well-loved and very active member of our community. she had a deep commitment to the environment and she will be so sadly missed".
"While we have come to some preliminary conclusions, I'm satisfied that from the briefing I've received from the homicide detectives as to the circumstances regarding that".
That incident was so shocking it ushered in tight gun control laws that have been held up as a global standard for preventing gun violence.
"Community centres have opened their doors to provide support", he said.