Australian police found up to five dead people including a woman and children on Sunday September 9 in a suburb of the western city of Perth, a senior officer said.
Western Australia police assistant commissioner Paul Steel told a news conference that up to five bodies were found at the scene when police arrived at noon. Investigators are still there.
He did not say how the people were killed or if any weapons were found. A man in his 20s was helping police with their inquiries, Steel said, adding there was no danger to the public.
Violent crime with multiple victims is rare in Australia but this was the second major incident in Western Australia this year. Seven people were shot and killed in the state in May.
Gun crime in Australia fell sharply after strict controls were introduced in response to a mass shooting in 1996, when a lone gunman killed 35 people in Tasmania.