A big shock for Winnipeg drivers on Wednesday with gas prices rising at many stations around the city.

Many raised their pump price to 122.9 per litre, an increase of 20 cents from Tuesday.

The unexpected partial shutdown over the weekend of an oil refinery in Indiana is believed to be a factor in the rise.

The BP Whiting Refinery in northern Indiana shut down the largest of three crude distillation units Saturday for what the company calls "unscheduled repair work." BP says the rest of the refinery is operating at reduced production.

"It's a big deal," said Patrick DeHaan, GasBuddy's senior petroleum analyst. "It's the region's largest refinery made up of multiple units, and this is the largest unit. ... The market is certainly (experiencing) some panic buying, and that's represented in retail prices."

For a list of local gas prices, visit GasBuddy.com.

- with files from the Associated Press