A major collision is slowing traffic on southbound Highway 2.

Traffic was reduced to one lane near the Deerfoot Trail and Macleod Trail split for several hours, with traffic backed up past the Dunbow Road exit.

RCMP were called to the scene at 6:24 a.m. after a passenger vehicle rear-ended a semi-tanker.

The driver of the passenger vehicle, a 44-year-old man from Okotoks, had to be extracted from the car and was airlifted from the scene by STARS air ambulance in life-threatening condition.

Collision reconstructionists were on scene for several hours, but the scene has now been cleared and traffic is flowing again.