Four people were taken to hospital after a multi-vehicle crash at a busy intersection.
Two of them suffered critical injuries, one of whom was airlifted to hospital.
Police said the cause was an SUV driving into a line of vehicles waiting at a red light.
One person needed to be extricated from their vehicle.
Police said it happened at around 10:48 a.m. on Tuesday at the intersection of Westmount Road East and Ottawa Street South.
Ottawa Street South was closed as a result, as was the northbound lane on Westmount.
The road was opened several hours later.
Debris littered the road in both directions.
Police were working to determine whether speed, distracted driving or a medical condition was the cause of the collision.
