Shoppers were trapped in a car park for more than three hours as they attempted to leave a newly opened Ikea store.
Frustrated customers were left beeping their horns as they struggled to get out of the multi-storey car park of the superstore in Reading. One man joked it was "easier to leave Europe than the Ikea Reading car park".
Rory Firth, 40, told the Press Association: "It was just bedlam. We were stuck for about an hour but a lot of people were stuck for upwards of three hours."
The father-of-two, from Maidenhead, Berkshire, said it was "a real nightmare".
He added: "We were on level one so we were quite lucky. I had my four-year-old and 10-month-old in the back seat so we were fortunate to get out when we did."
Stacey Barber, 22, from Farnborough, Hampshire, said the three-hour delay had ruined her day's shopping.
She said: "We were stuck for three hours and we only went to return something. We didn't get home till six so all the shops were shut and missed out on a whole afternoon."
Barber added that staff handed out bottles of water but had "no idea what they were doing".
She said: "After an hour everyone had enough. It was so hot and a bottle of water goes so far. People started arguing with staff saying 'what is going on?' and they had no answer.
"There were people with two or three kids in the car so they were getting more annoyed. People just kept beeping their cars to get attention but all we got was 'sorry for the delay'."
The store in Reading is the first Ikea to open in the UK in seven years.
Manager Johanna Heuren said a "traffic management plan" would remain in place while they investigated the cause of Sunday's delays.
Heuren added: "We can confirm that there was a delay with regards to customers exiting the Ikea Reading car park on Sunday afternoon. The number of visitors to the store was in line with the previous busy days during the opening weekend where our traffic management plan worked efficiently as planned.
"Our traffic management team responded to keep cars moving as quickly as possible and we'd like to thank customers for being patient and understanding of the situation."
In 2005, several people were injured and others suffered heat exhaustion following the opening of an Ikea in Edmonton, north London.
Around 6,000 people - triple the number expected by the company - descended on the store, forcing it to close its doors temporarily.