RCMP Sgt. Barry Kennedy says officers arrived at the restaurant in Princeton on Wednesday afternoon and found two women suffering from stab wounds and a man trying to cut his own throat.
BC Ambulance spokeswoman Kelsey Carwithen says the patients were taken to hospitals in Princeton, Kelowna and Penticton, and that one of them was transported by air ambulance.
Kennedy says police want to speak with witnesses.
He says people who may have seen what happened were gone by the time officers secured the scene and provided medical care.
Members of the Penticton RCMP's serious-crime unit are assisting Princeton police with the investigation.