The rollover happened after a small car lost control and collided with the truck around 11:20 a.m., according to Sgt. Kerry Schmidt with the Ontario Provincial Police.
Two people in the car and three people in the truck suffered minor injuries, Schmidt said, They have been taken to the hospital as precaution.
Drivers are using the collectors lane to pass the collision. Schmidt said travellers should expect delay on Highway 401 in Scarborough for at least the next three hours.