UNiT 1 WAS HEADING SOUTH ON THE WACAMMAW RIVER SOUTH OF MARKER 14 (SOUTH OF PITCH) 5 PASSENGERS TOWING 3 PEOPLE ON A TUBE. UNIT 2 CAME UP WACCAMAW/NORTH. WAKE OF UNIT 2 CAUSED THE TUBE TO GO INTO TREE. VICTIMS 1, 2, 3 WERE TAKEN TO GRAND STRAND HOSPITAL FOR TREATMENT.