Three people were taken to hospital after a rollover on the Minnewanka Loop in Banff at around 3:50 a.m. on Wednesday.
RCMP said a vehicle heading east rolled and ended up on the still-frozen Two Jack Lake.
Cpl. Curtis Peters said the three occupants of the vehicle were taken to hospital and the driver was later transferred to Calgary with more serious injuries, although they are not believed to be life-threatening.
RCMP are still investigating the crash.