Emergency services attended the scene of several multi-vehicle collisions in the vicinity of Myrniong on Monday due to extremely foggy conditions.
Approximately 30 vehicles were involved in multiple collisions on the Western Freeway about 4pm.
One collision, where no one was seriously injured, involved about14 vehicles.
Five other separate collisions took place in the surrounding area, also on the Western Freeway.
Two males were taken to hospital in a critical condition, each involved in separate collisions.
Twenty other people from various collisions were treated for non-life-threatening injuries.
The cause of the collisions appears to be due to heavy fog in the area and drivers not driving to the conditions.
Police are urging motorists to slow down due to reduced visibility in the area and to drive to the conditions and take note of any road safety signage in the area.
Anyone with information can contact Crime Stoppers on 1800 333 000 or www.crimestoppersvic.com.au.