Police say they were called to a store at the south end of the plaza located at 100 The Boardwalk at around 9:45 p.m.
Police say a woman was attempting to steal merchandise when she was approached by store staff.
The suspect flashed a knife before taking off in a waiting vehicle.
The vehicle, which had been reported stolen, was described as a 2018 Dodge Ram cargo van, grey in colour.
The suspect has been described as white, around 20 years old, five-feet-five-inches tall, with an average build and dark shoulder-length hair. She was last seen wearing a red jacket, purple shirt and black pants.
Police are asking anyone with further information to call 519-570-9777 or Crime Stoppers at 1-800-222-8477.
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