The derailed train belongs to Montreal Maine & Atlantic, which owns more than 800 kilometres of track serving Maine, Vermont, Quebec and New Brunswick, according to the company's website.
CBC's French service, Radio-Canada, has reported there was no one on board the train, which was being remotely operated.
The cause of the derailment is under investigation. A spokesperson for Quebec provincial police said it is still too early to say what could have caused the deadly incident.
The train "somehow got released," and had no conductor on board, according to the rail company. The convoy of crude oil left the station of its own accord during a shift change in Nantes, west of the affected region.
"We're not sure what happened, but the engineer did everything by the book. He had parked the train and was waiting for his relief," Montreal, Maine and Atlantic Railway, Inc Vice President Joseph McGonigle said on Saturday.
Train derailments carrying petroleum products in Canada have not been uncommon in recent months. An accident last week in Calgary, Alberta saw a train derailed on a collapsing bridge, threatening to send the diesel-carrying cars into the swollen Bow River.