Criminal probe opened into Quebec train derailment (VIDEO)

Canadian authorities opened a criminal investigation Tuesday into the deadly derailment of a train in Quebec, saying they have evidence the train may have been tampered with.

Police Inspector Michel Forget said investigators "discovered elements" that led to a criminal probe, but would not go into specifics.

More from GlobalPost: Quebec train derailment sets small town ablaze, kills at least 3 (VIDEO)

He did rule out terrorism in the fiery wreck that has claimed at least 15 lives.

Investigators have said they are trying to figure out whether the oil train's brakes were disabled before it barreled into the small town of Lac-Megantic early Saturday, causing a massive fireball to tear through downtown.

Firefighters in nearby Nantes put out a fire earlier on the train.

More from GlobalPost: About 40 people considered missing in Quebec train disaster

Ed Burkhardt, head of the Montreal, Maine & Atlantic Railway, blamed those firefighters for the derailment, telling media outlets there's evidence the engine powering the brakes was shut down at some point.

The news comes as officials began allowing some of the 1,200 Lac-Megantic residents evacuated by the explosion back to their homes, the Montreal Gazette reported.

About three dozen people remained missing Tuesday, with authorities saying some victims were likely vaporized by the intense blaze that burned for 36 hours after the crash.