The bodies of two young girls have been found inside their Madeley home with their mother under police guard in hospital.
The sisters, aged 6 and 10, were discovered by their father at their Bogdanich Way house around 6pm on Friday.
Their mother was located with self-inflicted wounds at a Whitfords beach carpark on Saturday morning and arrested.
WA Police said they attended the Madeley property following calls from concerned neighbours who heard screaming.
The bodies of one of the girls was first discovered by their father, who called police.Credit:Brandon Barry
"This is a tragic event and our heartfelt condolences go out to the friends and family of these children," he told reporters.
"Heartbreaking events like this not only have impact on those directly involved, the friends and family of those children, but on the wider community of Western Australia.
"Our thoughts are also with those first responders who discovered the bodies of those children and also for the forensic officers and the homicide investigators who will be working their way meticulously through this crime scene for the coming days and weeks."
The mother is currently under police guard at a Perth hospital, receiving medical attention and is unable to be interviewed by investigators.
Neighbour and family friend Gordana Sousak told Nine News Perth reporter Darius Winterfield the girls' father made the grim discovery of one of the bodies, before he was told by police to not go any further into the house.
When police arrived at the scene, they discovered the body of the second girl.
Police are yet to confirm details of how the girls were found.
"It’s just a shock, [the family] are devastated," Ms Sousak said.
"[The grandfather] told me his son came home from work to find his little girl dead on the floor.
"When he called police they told him not to touch her, but by that time he'd found the other little girl in the laundry."
Ms Sousak said the suburban area was a close-knit community and the street was filled with young families, most of who knew each other.
Another resident nearby said she heard screams coming from the property around 6pm Friday and called police.
A mother-of-three who lives across the road from the property and only wanted to be knows as Didi said she did not have a close relationship with the girls' mother but said her kids "played with her kids".
"She [the mother] just watches her kids on her side and my kids because we are scared of passing cars. My kids and her kids we are all just talking," she said.
"The husband is nice. He helps, brings the kids out they are together out sometimes. It's a surprise."
Both girls attended Ashdale Primary School, which was notified about the tragic events by police.
SUSPICIOUS DEATHS: Two people have been confirmed dead at a home in Madeley and one person is assisting police.
Darius Winterfield is at the scene and has more information.
Homicide detectives were at the scene in Madeley on Saturday trying to piece together the circumstances of the deaths.
The tragic events in Madeley, north of Perth, are the fourth family tragedy in the past two years in Western Australia.
In September 2018 Anthony Robert Harvey, 25, brutally murdered his wife Mara, 41, his three-year-old daughter Charlotte, two-year-old twins Beatrix and Alice and his mother-in-law Beverley Quinn in an inner-city Perth suburb.
Teancum Vernon Petersen-Crofts, then 19, stands accused of murdering his mother Michelle Petersen, 48, his 15-year-old sister Bella and eight-year-old brother Rua in July 2018.
And in the biggest mass shooting since the Port Arthur massacre in 1996, police found a mother, grandmother and four children slain on a rural property near Margaret River, in WA's South West in 2018.
More to come.