The truck was crushed by the massive beam, but officials say the driver managed to climb out of the vehicle and was taken to hospital with non-life-threatening injuries.
RCMP say the truck driver arrived at the mall around 8:30 a.m. PT to pick up garbage bins.
As he exited the garbage area, he drove forward, forgetting that the back-end of truck was still up.
The truck collided with the beam overhead, causing it to fall.
Paramedics say the driver called 911 himself from inside the truck before climbing out of the vehicle.
Police, fire, ambulance and Work Safety BC are on site assessing both the truck and the beam.
The Coquitlam Centre Mall remains open, although the West entrance to the mall is closed.