Fuming motorists argued, and tempers flared as traffic was reduced to a standstill at Gloucester Quays on Saturday.
Police were told by concerned callers that irate drivers waiting to leave the outlet shopping centre were arguiung as they waited hours to get out of the Quays car park.
Officers alerted highways officials because there appeared to be a problem with traffic light sequencing on St Ann Way during the afternoon.
One shopper, Catherine Hewer, said it spoiled a good day out at the shopping centre's Victorian Market event.
"It was horrendous," said Catherine, from Frampton-on-Severn.
"I didn't move the car for two hours. There were people with babies and small children who had to get out of their cars and get food.
"I had to leave to get something to eat. I got in the car at 4.10pm and got out of the Quays at 7.15pm.
"It was really nice to see it busy but I won't go there again. It was ruined by this delay."
A police spokesman said the force was called twice by people concerned at the length of time it was taking to get through the lights on St Ann Way.
One caller said they had seen people arguing in the queue to get out, while another told police people were becoming irate at the wait, just after 5pm.
He said a Police Community Support Officer was sent to the scene to help control traffic but highways officials arrived shortly after and the queues started to ease from around 5.30pm.
A spokesman for Gloucester Quays said: “In light of the unprecedented number of visitors over the weekend which far exceeded our predictions, we’re really sorry some experienced problems getting to and from the Victorian Christmas Market.
"We had contingency plans in place for additional parking as well as signage and traffic management systems – but we apologise to those experiencing delays. We will work closely with highways and other third parties to find a solution to traffic problems in the City particularly sequencing the traffic lights for our future events as Gloucester Quays is firmly on the map as a location for quality events and it’s clear that we’re attracting a larger number of visitors to the area than ever before.”