A 19-year-old man was charged with the murders of a 15-year-old girl, her eight-year-old brother and their mother.
A 19-year-old man has been sent for a mental health assessment after being charged with the murders of an eight-year-old boy, a 15-year-old girl and their mother at a suburban Perth house.
The boy and his 48-year-old mother were found dead inside the Ellenbrook home and the teenage girl was found critically injured in the backyard but died on the way to hospital on Sunday.
Teancum Vernon Petersen-Crofts appeared before Midland Magistrates Court on Monday to face three murder charges.
He will face Stirling Gardens Magistrates Court next week.
Assistant Commissioner Paul Steel told reporters in Perth on Sunday a senior homicide squad investigating officer had said it was "potentially the most horrific crime scene he has ever been called to".
"It is a very complex and I would say horrific crime scene."
"It's a crime that I know will send shock waves throughout the community of Western Australia.
"This is a terrible tragedy for the family involved, for their extended family and for those first responders who were forced to attend what was a horrific crime scene."
Police were initially called about 1.30am on Sunday to a convenience store on The Broadway before they went to the home. Both are still being processed as crime scenes.
A man who lives in a neighbouring street earlier told The West Australian he was woken up by screaming and yelling about 1am.
“It was real loud screaming and yelling, it sounded pretty heavy,” Matthew Schreck said.
If readers have any concerns regarding mental health, Lifeline Australia can be reached on 13 11 14.