Kate Malster was paying for her groceries when she saw a woman with a full trolley running full speed towards the exit of the Greenlane Countdown.
Employees from Countdown were shouting "stop, don't do this" to the woman before she exited the store.
Malster heroically chased the woman into the car park of the Greenlane supermarket, attempting to grab the trolley and telling her to stop before she escaped.
The woman reportedly pushed the trolley to two other people that were waiting at the rear-end of the getaway car and unloaded the goods.
"I have never seen food go so fast from a trolley into the back of a car... It was absolutely orchestrated so this definitely isn't their first time," said Malster.