WA police hope to learn within days what caused the death of a young boy, whose mother says she found him in a washing machine.

St John Ambulance officers arrived at the home Hilton, near Fremantle, shortly before 2pm on Monday after the woman said she'd discovered her three-year-old son unconscious in the washing machine.

Detective Senior Sergeant Doug Nelson, of the Fremantle district crime team, said the boy was taken to Fremantle Hospital where he was pronounced dead.

Forensic investigations were continuing at the scene on Tuesday and a post-mortem examination was carried out.

The boy's mother and "several members of the family" were interviewed at Fremantle police station, Sen Sgt Nelson said.

"It's very distressing for everyone who's concerned," he said earlier.

"Obviously, for the family of the young boy who's passed away, the first responders who have to attend, the St John staff, the medical staff and also the young police officers and the detectives who have to deal with it.

"It's distressing for everyone. So, obviously, we have things in place to assist people who are affected by it where we can.

Police have confirmed they are treating the matter as suspicious.

Neighbours described the boy as having blond-hair and blue-eyes.



"I saw him as a little baby, as neighbours do," one neighbour, Daniel, told the West Australian.



"He was quite a vibrant little fellow, with bright blue eyes, a happy little smile as he grew up."