FIVE people have been found dead at a home in Perth's northern suburbs.
In a statement, WA Police said the man walked into a regional police station and "provided some information" which led police to attend the Coode Street home.
The age and gender of those found has not yet been revealed, although it is thought "there was at least one woman".
Mr Steel said it was still unclear how long the bodies had been at the house before they were discovered.
He said forensic teams were on the scene and investigators were trying to piece together a timeline of events.
He said a man aged in his 20s is in custody, assisting detectives with their inquiries.
'Sadly at that location police have located the bodies of a number of deceased people including women and children, ' he said.
Investigators are now searching the home for evidence, and police could not provide any further details on the victims.
Assistant Commissioner Steel assured the community there are no ongoing safety concerns.
"Just a normal family, you would never imagine anything like that happening", he said.
Entire blocks around the crime scene at the corner of Coode and Fort streets are cordoned off and dozens of police officers are at the scene.
The bodies of Peter Miles, 61, his 58-year-old wife Cynda, their daughter Katrina, 35, and her four autistic children with estranged partner Aaron Cockman - Taye, 13, Rylan, 12, Arye, 10, and Kadyn Cockman, 8 - were found at the Miles' Osmington property in Western Australia.
Steel stressed that this was very early in the investigation so he could not provide many details.
Neighbors said they often saw children playing in the front yard of the home.
Forensic police and the homicide squad were undertaking a "meticulous" investigation of the Bedford crime scene which "could take a number of days".
"It does send a ripple through the community of Western Australia".
"It is a tragic thing when incidents like this occur".
We are three hours into this investigation.
The deaths follow the murder of a mother and her two children in Ellenbrook in July, and the Margaret River mass shooting that left seven people dead in May.