Three people lost their lives after the car they were travelling in overturned several times on Sunday night.
The deceased were thrown out of windows after the driver lost control of the fast-moving vehicle at Unit 13 near Mafikeng, police spokesman Emmanuel Reetsang said.
The other four passengers were taken to hospital with serious injuries.
Reetsang said cases of culpable homicide and reckless driving have been opened.
The names of the deceased are being withheld until their next of kin have been informed.