Two parents and their children have been found dead in the Perth suburb of Mosman Park in a suspected murder-suicide, police say.

At 8.15am on Friday, emergency services received a distressed call from a person known to the family who had gone to the home on Mott Close, in the city’s south-west.

Police arrived at the home to find the bodies of two adults, a man aged 50 and a woman aged 49, and two boys aged 14 and 16. Three deceased pets were also found at the house, located in a cul-de-sac in one of Perth’s most affluent suburbs.

“It is believed these persons are known to each other and are part of the family unit,” Det Insp Jessica Securo said on Friday.

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WA police’s Jessica Securo described the suspected murder-suicide in Mosman Park as a ‘confronting’ and ‘highly distressing’ scene. Photograph: AAP

Securo said it did not appear to be a “violent incident”, saying no weapon appeared to have been used.

“The family have no reported family violence matters with police,” Securo said.

Securo added that both children had “significant health challenges” and had engaged with care services in the past. She declined to comment further about these health concerns for privacy reasons.

Securo said the deaths were being treated as a murder-suicide because a note had been found at the house.

“Yes, there was a note left at the premises although I’m not about to go into the content of that letter, it will form part of our investigation,” she said.

Police will investigate whether the health challenges faced by the children was a factor in their murders.

“That will form part of our investigation. We will look at this holistically to see what led to this incident and go from there,” Securo said.

Police were piecing together the timeline of events, she said. The family were found after a person arrived at the home for an appointment on Friday morning, but it was unclear when they were last seen.

“What will form part of our investigation is – did this incident happen this morning? Did it happen last night? How long have those persons been in that house?”

Securo said the bodies of the family members were not found together, but all of them were inside the property.

“I can’t go into those details as to their exact location, however, I will say that they weren’t in the same location,” she said.

A spokesperson for St John Ambulance WA said it send five crews to the house this morning just before 8.30am on priority 1 conditions, which reflect potentially life-threatening calls.

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The Mott Close home is in one of Perth’s most affluent suburbs. Several streets in the coastal suburb were closed as police investigated the suspected murder-suicide. Photograph: Richard Wainwright/AAP

Securo described it as a “confronting” and “highly distressing” scene.

“The officers are understandably in shock after being confronted with such an incident like this,” she said.

“It’s not often that our officers come across such a tragic event with this many persons deceased.

“That’s why we employ a health and welfare 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 OK.”

Police remain at the home, with several surrounding streets cordoned off.

Kate Chaney, the federal MP for Curtin, which includes Mosman Park, said in a statement that the suspected murder-suicide was “shocking and devastating for our 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 and if needed, reach out to … services for support.”

 In Australia, the national family violence counselling service is on 1800 737 732. The crisis support service Lifeline is 13 11 14.