The air ambulance has been dispatched to Gumbuya World following a serious collision.
The Princes Freeway is closed outbound through Tynong North.
Motorists are being urged to follow the direction of Victoria Police and detour via Nar Nar Goon-Longwarry Road.
According to VicEmergency, as of 5.45pm on Monday 25 January, 10 vehicles are on scene responding to the incident.
An Ambulance Victoria spokeswoman confirmed the air ambulance had been dispatched.
Victoria Police is expected to provide an update shortly.