The Tesco store in Craigavon has been forced to close.
Store bosses were forced to vacate the premises after a technical issue this afternoon.
It will come as a huge blow to the 24-hour outlet on a busy Saturday.
It is understood that all of the tills at the Highfield Road store went offline at the same time.
Customers had to abandon shopping as they are unable to move through checkouts.
It is expected to cost Tesco a considerable amount in weekend trade.
The store has since reopened.