Canadian freight train explodes Saturday, killing at least five and at least 40 more people are still missing.

The Canadian freight train that exploded was carrying crude oil when it derailed after it started to move downhill without a driver on board. As it picked up speed, it hit a curve and came off the tracks at 1 a.m. It crashed into a town outside of Quebec.

Each tanker carried 30,000 gallons (113,000 liters) of crude oil. Four cars caught fire and exploded in a huge orange and black fireball that mushroomed hundreds of feet into the air and flattened dozens of buildings, including a popular bar, according a report from Reuters.

"Every time the Surete (Quebec police) needs to investigate, we need to rule out any foul play," spokesman Benoit Richard told reporters. "Right now we cannot say it is a criminal act. We can only say we are looking at it as if it was."

The death toll was originally at three, until police discovered more bodies.

"Two more people have been recovered, two more bodies, which brings the total to five ... there are about 40 people, more or less, who are considered to be missing," police spokesman Michel Brunet told reporters.

Police aren't sure of why the train started heading downhill out of nowhere as the train was headed from North Dakota to eastern Canada.

"That's the first thing I would think of: did someone release all the brakes?" asked Gary Landrio, a Warren, Pennsylvania, railroad consultant with 37 years of industry experience told Reuters. "In my experience, a train doesn't just simply let itself go down the hill into a town. There's usually a cause behind it."