Emergency services responded to a two-car collision in Narre Warren on Friday, 17 August.
It is believed a car was turning right onto Princes Highway from Lauderdale Road when it was struck by an oncoming vehicle about 10pm.
A man and woman in the turning vehicle were trapped for some time and taken to hospital in a serious condition, however the extent of their injuries is not known at this stage.
The driver and sole occupant of the other car, a 24 year old Officer man, sustained minor injuries.
The exact cause of the collision is yet to be established and the investigation is ongoing.
Anyone who witnessed the incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.