Five cars on the southbound train, including two containing crude, derailed at slow speed about nine miles (14 km ) east of Whitecourt, Albert, CN spokeswoman Emily Hamer said. She said the cause was still under investigation.
Slight seepage from the valve on one of the cars has been stopped and secured, Hamer said.
The remaining three cars were carrying paper and forest products.
The derailed cars were lying on their side, according to Whitecourt fire chief Brian Wynn.
Emergency and environmental response crews were on site, officials said. The Transportation Safety Board said it has deployed an investigator to the site. (Reuters)