Drivers are facing miles of tailback queues as Black Friday shoppers gridlock the routes into Bicester Village.
The shopping outlet, which stays open until midnight today, is working with police to ease the traffic.
But the major routes have been clogged up all afternoon and police are still advising people to avoid the area.
A spokesman for Bicester Village said it had to restrict access into the car parks for a 30-minute period.
She said: “It took us by surprise because we didn’t think people would be here so early and for such an intense period.
“It was very unexpected but the worst has happened. There are spaces in our car park and the shopping experience will be very relaxed.
“Traffic has now resumed to normal – just normal, busy, Friday afternoon traffic.”
There is very slow moving traffic on the M40 between junction 10 and 9 southbound and the A41 to Bicester is gridlocked.
Cars on the A34 northbound from Peartree Roundabout are all stationary.
Supt James Templer said: “We know it is very busy and we are working with our partners in Oxfordshire, and Bicester Village itself, to try and alleviate the pressure.
“I would recommend that people avoid the area if they can.”
Police are asking people stuck in traffic not to call 101.
Regular updates will be given through local radio and Twitter via the Roads Policing account @tvprp