RCMP Cpl. Robert McDonald says the crash happened just before noon on Saturday when a car stalled on the bridge.
He says an approaching car crashed into the stalled car, so both drivers got out of their vehicles and agreed to meet off the bridge to exchange information.
But before they could move, a taxi struck the second car.
The impact critically injured a passenger in the cab and left the driver of the second car a paraplegic.
McDonald says people should remain in their cars and call for assistance if they run into trouble on a bridge.
"The only time a cell phone would be of great value and that's if you are stalled or get into an accident on the bridge, remain in your vehicle and use your cell phone to call for help," he said.
Police are asking for witnesses to call the RCMP's Deas Island Traffic Services.