If you're driving in Western Canada and need to get gas, don't be surprised if your local Petro-Canada station doesn't have any.

Many Petro-Canada outlets in four provinces were either out of gas or quickly running out Friday morning.

Sneh Seetal, spokeswoman for Suncor, Petro-Canada's parent company, says an unplanned outage recently at its Edmonton refinery is contributing to the gas shortage.

"The part of the refinery that experienced the outage produces gasoline. As a result, gasoline production is substantially reduced," Seetal said.

"Because of this situation, we've had to temporarily curtail the volume of diesel and gasoline for our customers in parts of Western Canada, and there will be a temporary shortage of supply."

According to Dan McTeague, senior petroleum analyst with GasBuddy.com, that refinery processes 140,000 barrels of oil a day and supplies gas to cities as far away as Thunder Bay.

McTeague said Friday he had counted 27 stations in Calgary and Edmonton that had run out of gas as of Thursday. He expects the shortages to spread to other retailers as Petro-Canada's competitors try to fill the gap.

McTeague said the oilsands production shutdowns caused by the Fort McMurray, Alta., fire also contributed to the problem.

Companies are switching the configuration of their fuel to accommodate the weather, and vehicle demand for gas is higher in the summer, says Jennifer Winter. 0:31

There will be shortages at Petro-Canada sites in Alberta, Saskatchewan, Manitoba as well as some sites throughout the B.C. Interior until the problems are solved, Seetal said.

"We are doing everything we can to improve the situation. The cumulative impact of the fires and the unplanned outage at Edmonton was unanticipated," she said.

"We are taking a number of steps. We are bringing in additional supply for our Edmonton refinery and we are also restarting our oilsands operations in a safe and staged manner."

Suncor also is bringing in additional gas from other parts of its network and other companies, and transporting it by truck and rail as quickly as possible, Seetal said.

Alternate supplies could be hard to come by at the moment, McTeague said.

"Beyond the fire at Fort McMurray, which may have slowed down oil production and the availability of oil, we also have a situation in the U.S. Midwest … where two or three refineries are also in a bit of trouble," he said.

"They've not been able to produce as much gasoline [at] the very time U.S. demand for gas is going through the roof."

The shortage was likely accelerated by the fact that analysts had forecast a spike in prices due to the U.S. supply disruption just before Suncor's refinery ran into trouble, McTeague said.

Jennifer Winter, the director of energy and environmental policy at the University of Calgary's School of Public Policy, said consumers shouldn't worry that the shortage will become a crisis.

"Suncor is going to be working as hard as it can to get the refinery back up, because it's losing profits," she said.

"This is just something that happens. Refineries have planned and unplanned outages."

McTeague said the shortage points to the need for the government to require producers to be more forthcoming about their inventories, as in the United States.

"I think Canadians and motorists are certainly owed a greater explanation and a greater degree of transparency," he said.