Shoppers were left red-faced when they were locked inside a B&Q.
The pair were spotted waving for help through the windows of a branch in Leicester on Saturday at 9pm
Onlookers soon raised the alarm, as one told LeicestershireLive: "They were waving at us and trying to tell us they couldn't get out.
"My partner contacted the police but they told him they would contact B&Q security as it was out of hours. I hope the couple are ok."
The shop closes at 8pm six days a week as staff had failed to see the pair were still inside before shutting for the day.
A spokesperson for the DIY store said there are processes in place to ensure stores are empty before closing - including loudspeaker announcements that they are about to close.
The witness said she has since complained to B&Q about their alarm systems, which she said "clearly needed to be updated" as they weren't set off by the pair locked inside.
A B&Q spokesperson said: "We have processes in place to ensure that stores are empty before closing.
"On Saturday evening, despite a store check and announcements, two customers remained inside the store.
"Our colleagues arrived on site to let the customers out within 15 minutes of being notified. We apologise for any inconvenience caused.”
Last year, a couple were so engrossed while trying out a new game inside a shop they ended up getting locked in as staff pulled the shutters down and left for the night.
Nathan Bamping and girlfriend Olivia Johnson were stuck inside a branch of Currys PC World for 40 minutes because workers failed to notice them as they left at closing time.
The pair had popped in to do some last-minute Christmas shopping and decided to try out a racing game on Xbox Series X.
Data analyst Nathan, 19, said: “We’d only intended to have a quick go, but it’s so addictive that we spent ages racing each other.
“When we finally got up we found all the doors were closed, the shutters were locked and the staff had gone."
A spokesman for Currys PC World apologised to the customers.
