The walkers, from Sheffield, were then carried some distance down a steep cascade before finally coming to rest.
One member of the party then managed to make his way to the Snake Inn to raise the alarm and the ambulance service called on the mountain rescue teams to help.
One lady in her fifties suffered head, chest and back injuries, including a fractured spine in the accident. Both the casualties were soaking wet and suffering from hypothermia.
After initial treatment by ambulance service crews and mountain rescue team medics, one casualty was helped back up the road while the more seriously injured walker was evacuated by stretcher. Both were taken by ambulance to the Northern General Hospital in Sheffield.