Canterbury Police are investigating the death of 1 woman and 3 children in Tinwald, Ashburton.
Police say they have a team of 30 staff working on the investigation including forensic staff.
Scene guards were in place overnight in the area while a full scene examination was carried out.
Inspector Dave Gaskin, Area Commander Mid-South Canterbury, says "This is a tragedy and there are a number of questions we are looking for answers for. Our thoughts are with the family at this time.”
The woman who died was born in the Cook Islands and she has been identified as Cyndi George. It is believed that George moved to Ashburton around 5 years ago to work.