Officers "discovered the deceased bodies of several people including children", police said in a statement.
Assistant Commissioner Paul Steel told reporters yesterday that a man in his 20s had turned himself in at a regional police station earlier in the day.
"The man now assisting police remains in custody, no charges have been laid at this time", police said in a statement.
The relationship of the victims to the man in custody is also yet to be confirmed.
"The homicide squad now have teams of detectives on the ground, accompanied by specialist forensic police who are meticulously working their way through this crime scene".
"It is a tragic thing when incidents like this occur", he said.
Assistant Commissioner Steel said police were trying to identify relatives to notify them.
As a result, police attended a home on Coode Street in Bedford today and made the grisly find.
Neighbors said a young family lived in the home and an older woman had frequently visited.
The police chaplain was at the scene providing support for police officers on Sunday.
"It's horrid to think that in such a handsome area, that's calm and so quiet, that something so tragic has taken place", she said.
It was not known how the victims died or their connection with the man in custody.
"Depending on the size of that crime scene that will take a period of time, and it could be a number of days", Mr Steel said.
"This is a tragic event and will have an impact on family and friends, the community, and the emergency services who first responded to the tragic scene".
Mr Steele called the discovery "heartbreaking" and said the tragedy would send a ripple through the wider community.
The incident comes just months after seven people were murdered at a home in Margaret River.
The age and gender of those found has not yet been revealed, although it is thought "there was at least one woman".
Gun crime in Australia fell sharply after strict controls were introduced in response to a mass shooting in 1996, when a lone gunman killed 35 people in Tasmania.