Traffic is still being detoured around the site — which happened at around 5 a.m. this morning.
Police say the driver of the car swerved into an oncoming truck carrying live chickens.
Both men in the car — aged 19 and 20 — were critically injured and needed to be cut out of their vehicle with the Jaws of Life.
They died in hospital.
The driver of the truck was unhurt but is being treated for shock.
Police believe the driver of the car may have fallen asleep at the wheel.
St.-Simon is about 250 km northeast of Quebec City.