A police spokeswoman said it appeared someone's foot had been caught under a brake pedal.
A St John spokeswoman said one patient was taken to Oamaru Hospital by ambulance in a moderate condition.
Simon Lye, managing director of Mitre 10 MEGA Oamaru, said late this afternoon that a staff member was injured while operating a forklift.
The man was qualified to use the machine and all safety protocols were being followed.
‘‘We take health and safety of our team very seriously and have notified WorkSafe."
The store would provide full support to the team member and looked forward to welcoming him back once he had recovered, Mr Lye said.