Mystery surrounds the death of a teenage mother in a tiny wheatbelt town of Western Australia.

It wasn’t until police came knocking late on Monday night that neighbours in Calingiri realised something was wrong.

“Being a small little community town, I think we’re a lot of people are still shocked to see what happened,” neighbour Clint Hansen told 9News.

“And you know, there’s that many different stories going around, so nobody actually knows what happened.”

Calingiri soon became a hive of activity as homicide detectives and forensic officers descended on Harrington Street, about 130 kilometres north-east of Perth.

Police say a triple zero call was made just before 9pm.

An 18-year-old woman was found unconscious inside a demountable home at the back of the block.

First responders did CPR, but the teenager couldn’t be saved.

A young baby was discovered uninjured in a bedroom.

9News understands the man who made the triple zero call was in an agitated state and and paramedics didn’t go inside until police arrived because of safety concerns.

Neighbours say the property owners only visited the town infrequently and the transportable home was erected on the block less than a fortnight ago.