Canadian police say that sixty people are now missing and feared dead after a freight train carrying crude oil exploded in Lac-Megantic, Quebec.

Officials ruled out terrorism as a cause of the runaway train but said that criminal negligence is under investigation. The entire downtown area of Lac-Megantic is considered a crime scene.

“There is an enormous task ahead of us,” Quebec Police Inspector Michel Forget told the BBC. “We’re not at the stage of arrests.”

The train was parked Saturday night seven miles away in Nantes, Quebec. A fire broke out on the train and local firefighters were called to put out the flames. During that effort, they reportedly turned off a locomotive that had been on to deploy the train’s brakes.

The train then began an 18 minute trip into Lac-Megantic where it derailed and exploded. Over 30 buildings were incinerated by the fireball from the train. Officials say some of the victims of the explosion were vaporized by the heat and have asked family members of those missing to provide DNA samples to help identify the dead.