Three people were taken to hospital after a six-vehicle crash involving a water tanker truck on the Queen Elizabeth Way near Dixie Road.
Emergency crews say they responded to the crash in the Toronto-bound lanes around 7 p.m.
Paramedics assessed nine patients on the scene and three were transported to hospital. Two men suffered serious, non-life-threatening injuries while a third patient had minor injuries.
The six others assessed did not go to hospital
Four of five lanes of the QEW are blocked as crews cleaned up the collision.