Police say a portion of Highway 11 near the Canada-U.S. border was closed in the early morning hours after a truck hit a car, sending it into a water-filled ditch.
Const. Paul Walker says the car was upside down when emergency crews arrived on the scene, and a number of citizens worked with officers to turn the car over so the four occupants could get out.
"It took about 15 people to right the vehicle," Walker said.
Three occupants of the car were treated for injuries at local hospitals while the fourth was flown to a Vancouver hospital with more serious injuries.
The accident is under investigation and police are looking into the possibility that alcohol may have been involved.