Regina police say a vehicle was travelling fast enough that when it hit another vehicle stopped at a red light, the force of the collision flipped a third vehicle onto its roof.
Officers were called to the intersection of Dewdney Avenue and Fleet Street in the city's east end around 2 a.m. CST on Sunday.
According to a news release, two of the vehicles involved in the crash were stopped at a red light at Fleet Street, waiting to head east. The third vehicle, also eastbound, came from behind them.
The first vehicle at the traffic light was the one that ended up on its roof.
Everyone in the three vehicles were hurt, police said. Four people had to be taken to hospital, including the driver of the third vehicle whose injuries are described as serious but not life-threatening.