Up to 12 cars have been involved in a smash inbound on the Monash.

All three lanes were initially blocked between Princes Highway and Narre Warren Cranbourne Road, now one lane is open. 

Massive delays already and five cars need to be towed. 

Emergency crews on scene, speed set to 40km/h.

Allow extra time and drive with care. 

UPDATE 7:25am: All lanes are now open and delays are starting to clear