A woman was flown to a Melbourne hospital after a quad bike rollover on Monday, November 17.
Police said it was believed the woman was herding cattle on a property on Centre Rd at Waaia when she came off the quad bike.
The woman was located by a passerby about 8.15am.
Ambulance Victoria advanced life support paramedics, mobile intensive care ambulance paramedics and the air ambulance helicopter treated the woman at the scene.
She was flown to The Alfred hospital by air ambulance with upper body injuries.
Police said her injuries were life-threatening.
An investigation into the incident is under way.
Any witnesses, or anyone with vision or information is urged to contact Crime Stoppers on 1800 333 000 or anonymously online at crimestoppersvic.com.au