It is understood the incident began inside the supermarket and continued in the nearby car park, where the injury was incurred.
It is also believed that the female staff member later sought medical attention for her injury.
A police spokesman said police were called to the supermarket about 7.20pm after an alleged shoplifter had reportedly been found at the store and "one person was arrested".
Full details of the incident were not immediately available, including exactly how the injury occurred, and the nature of the injury.
It is understood one police officer initially arrived at the scene. Other backup police quickly appeared at the supermarket.
The spokeswoman said because the matter had just happened, it was also too early to determine the details of any charges that might be laid arising from the events.
