Homicide Squad detectives are investigating the circumstances surrounding the death of a woman in Mill Park on Thursday evening.
Emergency services were called to an address in Kellaway Crescent about 7.50pm after reports of a stabbing.
On arrival police located a man, woman and a girl with critical injuries.
The woman died at the scene and the man was taken to hospital under police guard in a critical condition.
The girl was also taken to hospital in critical condition.
At this stage detectives believe all parties are known to each other.
Anyone who witnessed the incident or with footage or further information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au