A woman has been critically injured in Feilding and police are trying to work out how it happened.
They say the 49-year-old sustained her life-threatening injuries on Thursday night and was taken to Palmerston North Hospital in a critical condition.
Detective Senior Sergeant Craig Sheridan says he is not prepared to comment on the extent of the woman's injuries except to say that they are critical and unexplained.
Mr Sheridan says he will be speaking to the woman's partner, family, and friends in order to piece together her movements before the incident.
Eighteen officers are working on the investigation as well as two forensic experts.
"Our roles today will include identifying and talking with family, close friends and neighbours," Mr Sheridan says.
"We need to be piecing together this lady's movements. We will be doing an examination of her house. We don't know a lot but we're determined to move forward and get to the bottom of of it."