West Auckland's newest hypermarket has been briefly plunged into darkness after an in-store power cut this morning.
Shoppers wandered through the cavernous Costco store in the dark after the lights went out unexpectedly before lunchtime a day after its grand opening.
Pictures have been posted to social media showing people in the food court continuing to eat despite the blackout.
Other pictures show shoppers continuing to wander through the aisles with trolleys.
A person at the store at the time said around half of the warehouse was affected, going completely dark for around five minutes.
The shopper said despite limited visibility people were still shopping and the tills were not affected.
"Even lights not working didn't put people off but when the lights went on again everyone cheered."
The shopper said sections in the store, such as the produce department, were still lit up, as were cabinet displays.
However, vast sections of the store such as the animated Halloween display and the electronics section were plunged into darkness.
Costco is being approached for comment.
The glitch came after a hectic 24 hours that saw police issue a warning to motorists of significant congestion on roads near the new Costco site which opened yesterday.
The big box retailer drew hoards of eager shoppers on its first day of operation in New Zealand, with queues out the door and bustling trade across the day.
A woman who arrived at Costco and joined the queue at lunchtime said it was taking about 40 minutes to reach the store's entrance.
The shopper said she arrived at 12.19pm to find the queue was beyond the end of the building.
Photos showed a long line of shoppers snaking around the Westgate complex and carpark.
Costco Wholesale, founded in 1983, has stores in the United States, Puerto Rico, Canada, United Kingdom, Mexico, Japan, Korea, Australia, Spain, France, Iceland, China and via a majority-owned subsidiary in Taiwan.
The chain had stores in 828 locations at the end of last year of which 572 are in the United States.
The Auckland warehouse is a $100 million-plus membership store, costing $60/person or $55/business annually.
It buys most of its merchandise directly from manufacturers and its strategy is to provide members with a broad range of quality goods at prices consistently lower than elsewhere.