Coles is now installing “Anti-Theft Fog” devices to deter thieves at stores around the country.
The extreme security measure works by letting off a cloud of heavy fog over the registers, checkouts and shelves whenever an alarm is triggered.
7NEWS.com.au understands that the technology is designed to go off when there is a break-in after hours, and makes it difficult for thieves to see what’s in front of them.
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However a “technical mishap” at one Melbourne store meant that customers were able to see the “smoke cloak” in action.
Sharing on Reddit, one shopper spoke out about the alarming experience at the Coles store in Clayton.
In their post, the customer said they were grocery shopping late at night when they noticed smoke fill the front of the store.
Photos posted by the customer show how the front of the store was clouded with smoke.
“Not sure exactly what happened as I was wearing my headphones and zoned out in my own world, but I stopped by my local Coles to grab something for dinner on my way home around 10:20pm last night,” they wrote.
“As I was walking to the checkout, I heard a loud pop and smoke gradually filling the store (there was no burning smell and everyone in the store was relatively calm, however the firm alarm did go off).
“The smoke eventually went away after two to three minutes. Does anyone know what it may have been?”
Many social media users were quick to confirm that the smoke was likely caused by the anti-theft device.
“Anti theft fog, it’s used to stop thieves,” said one.
Another wrote: “Theyre meant to go off if the store is broken into/ram raided after closing time as its nearly impossible to steal stuff when you cant see s***.
“Definitely a malfunction if it was during open times.”
A third said: “It’s called a smoke cloak.”
The shopper who shared the images said they had no idea such a device existed.
“Thank you to everyone who took the time to clarify that it’s a security/anti theft mechanism,” they said.
“I genuinely had no idea that they used them at grocery shops!”
7NEWS.com.au understands that there is no health risk associated with the fog technology.