“The family had engaged with care services but I’ll leave it at that at this stage.”
Three pets – two dogs and a cat – were also found dead at the property.
Officers were called to the property by someone known to the family, who had a prearranged appointment at the home.
Inspector Securo said it was not yet known when the tragedy occurred.
“At this stage, I’m not able to disclose how these persons are deceased,” she said.
“However, I do reiterate that there doesn’t appear to be a violent incident that has occurred at the house.”
Police also confirmed the family had no prior reported domestic violence issues and no weapon was used.
“At this stage, there’s two parents and two children, so we will treat it as a double murder-suicide,” Inspector Securo said.
“There is no ongoing risk to the community. What I can advise is that there was no weapon used during this incident, and the family have no reported family violence matters with police.
“This tragic incident occurred only this morning and it will take time to investigate the full circumstances surrounding this incident.
“We urge members of the public to stay away from the area and be mindful that several streets in its vicinity are blocked.
“This is a highly distressing situation for all involved, from community members to the person that located the family to our first responders.”
Inspector Securo would not go into the content of the letter found at the property, but said it would form part of the police investigation.
“I can’t go into the details or the contents of the note, or who wrote it,” she said.
The investigation is ongoing, with homicide detectives examining the scene, reviewing CCTV, canvassing neighbours and conducting a full forensic assessment.
Inspector Securo said officers who attended the scene were in shock.
“It’s not often that our officers come across such a tragic event with this many persons deceased,” she said.
“That’s why we employ our health and welfare teams, and our police chaplain, to attend the scene as soon as possible, speak to the officers, wrap our arms around them, and make sure they are okay.”
The surrounding area has been cordoned, with police urging the public to stay clear.
Member for Curtin Kate Chaney said the news was “shocking and devastating” for the community.
“My thoughts go out to the friends and relatives of this family, as well as the first responders, and the neighbours and local community who knew them,” Chaney said.
“This heartbreaking loss of four lives will have lasting effects throughout our community.
“I hope the police investigation will provide more information soon about the circumstances that led to this tragic event.
“I encourage everyone impacted by this news to hug their loved ones.”
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