Similar incidents had occurred at the Chapel Road Shopping Centre, Meadowlands Shopping Centre, Flatbush and Pakuranga.
In each case the victims had been carrying large amounts of cash in their handbags.
Police advised anyone doing last minute Christmas shopping or heading out on Boxing Day to use credit or debit cards to avoid carrying large amounts of cash.
Shoppers were also advised to lock their handbags in the car before unloading any other shopping in the boot or back seat.
"Our concerns are that the level of violence that the offenders use could escalate very quickly, meaning there is a very real risk of a victim being seriously injured," Mr Wilkinson said.
"I'd like to get the message across to the community that if you are targeted in this type of attack, you should not try to hang you're your bag. Just let it go, ring 111, and make a note of any descriptions of vehicles and offenders."