A freight train transporting crude oil from Canada to the United States derailed in eastern Québec on Saturday, sparking several explosions and a fire that destroyed the center of the town of Lac-Mégantic (population: 6,000).

Officials said at least 13 people were killed, with another 30 or more unaccounted for, as of Tuesday morning. The accident forced the evacuation of about 2,000 residents from the town, located only 10 miles from the Maine border. Of these, 1,200 were allowed to return to their homes on Tuesday.

The train’s engineer had parked the five locomotives and 72 tankers in the town of Nantes, approximately seven miles from Lac-Mégantic, for a crew change before retiring to a nearby motel for the night.

Representatives of the operator of the train, the Montréal, Maine and Atlantic Railway, said they couldn’t be sure how the train managed to travel on its own. But officials speculated that the train's air brakes may have malfunctioned, allowing it to roll out of control until it derailed at the centre of Lac-Mégantic.

It is still not known how many people were killed, how many buildings were destroyed and whether the town’s water supply has been contaminated by the more than 26,000 gallons of light crude oil that spilled into the Claudiere River, which feeds into the St. Lawrence River.

Montréal, Maine and Atlantic Railway is owned by Rail World Inc., an Illinois-based privately held rail management and investment firm founded and headed by Edward A. Burkhardt. The crude oil was loaded onto the train at the Saint John refinery in New Brunswick and was headed to Maine.

-Noel Brinkerhoff, David Wallechinsky

To Learn More:

Key Things Confirmed in the Lac-Mégantic Train Blast (CBC News)

Lac-Mégantic Timeline (Montréal Gazette)

Leaking Oil from Lac-Mégantic Disaster Affects Nearby Towns (CBC News)

Train Company in Quebec Derailment Headed by Chicago Rail Veteran (by P.J. Huffstutter and Scott Haggett, Reuters)

1 dead, People Missing after Oil Train Derails in Quebec (Associated Press)