A Mitre 10 spokesperson told the Herald that staff were alerted when they saw the person ignore procedure and made a B-line straight for their car with goods in hand.
"Our staff realised when the customer didn't retreat to the evacuation point and jumped straight into their car.
"When the drill was over we then realised that the person had left with their goods without paying."
The spokesman says they're disappointed someone would abuse a situation that's designed to keep customers safe during emergency events.
"We are very disappointed that someone has taken advantage of us during a fire drill, we have very strong systems and process to mitigate and control shrinkage in our business.
"However, on this occasion during a fire drill our focus is on our team and customer wellbeing and you can't legislate for someone being as opportunistic as this person was.
"In these unprecedented times for retail, it's the principle that upsets myself and the team the most. We have learnt a valuable lesson which will be carried into future drills."
Despite pleas on social media from Mitre 10 for the suspect to come and settle the matter, the person has not yet made contact.
Mitre 10 have handed a "crystal clear photo" of the suspect over to police.
Customers rallied around the store, calling out the alleged thief for their actions.
"That is shocking. Sad you have had this happen to you. We love going to your store, such friendly staff. Hope they catch the thief," one person said.
Another saw the opportunity for some criminal wordplay, writing: "Hopefully he will be able to measure the pressure he is under and clean up his act with the organiser."
A third added: "Shame on you. That store is great. And the staff are amazing always helpful and friendly."
Police confirm the incident happened around 7.40am and are looking into the matter.
