The exact ages and genders of the victims are unknown but at least one of them was a woman, police said.
Metropolitan region Assistant Commissioner Paul Steel said earlier this morning a man in his 20s presented to a regional police station, which he would not name due to the "highly emotive" nature of the situation, and was taken into custody.
Police arrived at the north-eastern suburbs property about noon WA time (2pm AEST), where they found the bodies of up to five people - including women and children.
"It is tragic not only for the family and the friends, it is also tragic for those first responders who are forced to attend such scenes", he said.
The incident marks the third tragic event in recent months in Western Australia.
"We understand there are children and adults involved".
It was later alleged that Peter Miles killed his family members before ending his own life, but that is yet to be officially confirmed by a coroner.
A number of police cars, homicide squad officers and forensic police are at the house.
Maria Manfredini, who has lived in the area for more than 30 years, said it was tragic on every level. The Assistant Commissioner assured the community there were no on-going concerns for public safety as a result of this incident.
He said forensic teams were on the scene and investigators were trying to piece together a timeline of events.
"I am deeply saddened by what had happened today", she said.
It is yet to be determined how long the bodies had been there, Mr Steel added.
"This is a very close community", she said.
A suspected massacre in a quiet Perth suburb has horrified residents who say the victims seemed like "a normal, happy family".
"It is a tragic thing when incidents like this occur".
The road is blocked off at the Coode Street and Beaufort Street intersection.
It also follows the deaths of seven people, also in Western Australia, when a grandfather shot dead his wife, daughter and her four children in a mass murder-suicide in May.