The five people found dead in a suburban Perth home are believed to be a mother, her children and their grandmother.

A man in his 20s surrendered himself at a regional WA police station, before officers visited a home on Coode St in the suburb of Bedford.

When police entered, they discovered the bodies of two women and three young children. Police refused to say what the man told them - or how he was known to the victims.

The West Australian newspaper reported late last night that the victims included a mother, her three young children, and the grandmother of the children.

The identities have not been confirmed by police, but upset neighbours told reporters at the scene a couple with three young girls - aged 3 and 18-month-old twins - lived at the address.

The family had not ben seen in recent days which has fuelled the anxiety of residents.

Assistant commissioner Paul Steel confirmed the victims were both adults and children, but would not clarify their ages or genders.

"This is a tragic event and it will no doubt have an impact not only the family and friends of the deceased but for the whole of the community, those first responders who are faced with attending a scene with multiple deceased people," he told reporters today.

"It does send a ripple through the community of Western Australia."

He said specialist forensic police would investigate the scene, which was stil at a "very early stage".

"We are three hours into this investigation, I have no further detail in relation to those who are present at the location."

WA Police told news.com.au the man was in custody and assisting policy with their inquiries. No charges had been laid by late last night.

"There are no ongoing concerns for public safety as a result of this incident."

A number of police cars, homicide squad officers and forensic police were at the house, with the road blocked off at the Coode and Beaufort St intersection.

A distraught neighbour told WA Todaythat she often saw children playing in the front yard of the house at the centre of police investigations.

"It's just so sad, they've got primary school aged kids and I thought it just couldn't be," she said. "How could someone do that to their own children? It's sickening to think someone could do that."

Another neighbour told WA Today she didn't know the home's occupants personally, but would often wave and say hello as she walked past.

"It's taken us by complete shock," she said. "It's just horrific on every level."

Neighbour Vagner de Souza told the ABC he regularly saw a family in the house's yard.

"Just a normal family, you would never imagine anything like that happening," he said.

The incident comes just months after seven people were murdered at a home in Margaret River.

In May, a family was murdered on a rural property in Osmington, on the outskirts of Margaret River.

The deaths of Katrina Miles, her parents Cynda and Peter, and children Taye, Rylan, Arye and Kadyn, were described as Australia's worst mass shooting since the Port Arthur massacre.

In July, Kiwi mum Michelle Peterson, 48, and her children Bella, 15 and Rua, 8, were killed in the suburb of Ellenbrook.