Mother, Two Kids Killed In 'Horrific' Crime In Perth

A detective said the scene was perhaps the “most horrific” he has seen.

A 19-year-old man is in custody after a mother and her two children were killed in a "terrible tragedy" at a home in Perth’s north-east.

Assistant Commissioner Paul Steel on Sunday said police responded to a call from a man to attend a convenience store in Ellenbrook about 1:30am on Sunday. Their inquiries led them to a nearby home.

A male and female were found dead inside, and another female was found in the backyard with critical injuries. The third victim died on the way to Royal Perth Hospital. Police have since confirmed the dead include a mother and her two children, a boy and a girl.

A 19-year-old, who lives at the house, is in police custody.

Police have not released details of what happened at the property, but officers called it a “horrific crime” and said it will send shockwaves through Western Australia.  

“A senior homicide detective squad officer said to me that it is potentially the most horrific crime scene that he has ever been called to,” Assistant Commissioner Steel said.

"This is a terrible tragedy for the family involved, for their extended family and for those first responders who were forced to attend ... my heartfelt condolences go out to all of those who have been affected by this tragic incident.

"I can assure members of the community that WA Police are applying all resources that we can to get to the bottom of what has happened here."

A "complex homicide investigation" is underway, with the home and the convenience store remaining active crime scenes. The assistant commissioner said investigations could take several days. 

He confirmed a 19-year-old man, who resided at the same address, is currently in custody and is being questioned by police.

"(His) relationship with the deceased, as well as any circumstances relating to that address, will form part of the ongoing investigation," Steel said.

Members of the public who believe they have information that could assist police in their investigation are urged to contact Crime Stoppers on 1800 333 000.