A major gas station has is running on empty.

Petro-Canada stations are almost out of gas.

That's because of a malfunction at the company's Edmonton refinery.

Jon Hamilton, a spokesperson for Petro-Canada, say the Catalytic Cracking Unit, which helps convert crude oil into gasoline, is broken, and no one is sure how it happened.

"With the cat cracker down we're a bit like a donut factory without a deep fryer. We just can't make the finished product, so we're taking additional steps."

Petro-Canada says it may start buying gas from competitors to keep retailers running.

It's also sending fuel trucks from Vancouver to restock interior B.C., which also relies on the Edmonton refinery, but Hamilton says that takes time.

"Drivers can only drive so many hours. You can only put so much into a truck. So we're basically trying to ease the pressure in B.C., ease it so we can maximize the gas available in Alberta."

Frank Atkins, an economist at the University of Calgary, says don't be surprised if this happens again.

"Refinery capacity in Canada and the United States is very, very tight. We have not built a new refinery in North America in the last 25 years, so these refineries, they're old and running at capacity all year long, so as soon as something goes wrong, small or big, it backs up through the system."

If the problem at the refinery doesn't get fixed soon, Petro-Canada stations in Manitoba and Saskatchewan may start to be affected.

They're also supplied by the Edmonton refinery, but they haven't run out of their current gas supply yet.

Petro-Canada says if it needs to, it may start supplying the prairies from the same refinery that supplies Ontario, which is in Montreal.