Staff at one of the affected stores at Sydney's Town Hall confirmed the outage meant customers were left with no choice but leave without purchases.
Stores temporarily closed in response to the outage.
"Registers are offline so customers are standing in queues with baskets of food that they can't buy", she said.
A woman named Rose, from Hoppers Crossing in Melbourne, told 3AW customers were offered lollies as they were asked to leave.
More than 20 shoppers were reportedly turned away by the security guard.
IShares MSCI New Zealand Capped (ENZL) Rises 0.06% for April 15
In terms of performance, shares of Direxion Daily MSCI Dev Mkts Bull 3X ETF (:DZK) are -1.52% since the start of 2016. The company had revenue of $334.80 million during the quarter, compared to analysts' expectations of $333.68 million.
Margaret River Pro surf event suspended due to nearby shark attack
Hawaiian pro surfer John John Florence had a close encounter while surfing in the region in the lead up to the competition. Opposition Leader Mike Nahan said the attack would make global news given the Margaret River Pro event was on nearby.
Americans have two extra days to file their income taxes this year
While 36% of respondents overall selected this answer, more women planned to pay off debt (40%) than men (33%). Whoever hasn't filed their 2014 tax return in the next four days will lose their share.
According to multiple reports, Woolworths supermarkets around Australia are experiencing a technical issue that prevents them from processing any transactions. The registers are now back online in all our stores.
Seven News in Adelaide is reporting that some customers at a Woolworths store in Adelaide's west got their groceries for free after the nationwide outage.
INITIAL: MAYHEM has erupted at Woolworths stores across the Mackay region as a national technical outage shuts down stores.
The supermarket giant has not yet revealed the cause of the outage.