A runaway train carrying crude oil sparked a series of explosions in the small Quebec town of Lac-Megantic, destroying half of the downtown core and killing at least one person.

At least 1,000 people were forced to flee their homes in the middle of the night as fireballs engulfed surrounding houses and buildings. The explosions jolted residents awake. Some initially thought that bombs were going off.

Several people have been reported missing, but fire and police officials say some of them may have been out of town at the time of the derailment.

Police said late Saturday that they expect to announce more fatalities as the investigation continues.

The fire continued to burn more than 20 hours after the derailment, preventing provincial and federal investigators from accessing what’s left of the train.

Fire Chief Denis Lauzon said the area surrounding the crash site looks like a “war zone.”

“A lot of buildings burned, trees and everything -- so it’s unimaginable,” he told reporters.

“Words cannot tell the damage that had been done,” Quebec provincial police Sgt. Gregory Gomez del Prado said. “Many, many buildings have been damaged. It’s a catastrophe for the town of course, but also for the whole province.”

How it happened

Montreal Maine & Atlantic Railway Inc., which owns the train, says it was unattended and “came loose” between 1 a.m. and 1:30 a.m.

A representative from the company told CTV News that the 73-car train was parked and secured in Nantes, Que., just west of Lac-Megantic, late Friday night. The two town centres are about 12 kilometres apart.

Joe McGonigle, a vice president at Montreal, Maine & Atlantic, said the train “came loose” in the early morning hours Saturday and “started rolling down the tracks.”

He said the train’s engine was found about one kilometre from where the explosions took place.

The train’s conductor, who was at a hotel in Lac-Megantic when the train derailed, is being questioned by police, according to McGonigle.

Witnesses reported hearing multiple explosions and seeing flames shoot up as high as 300 feet.

“I heard people say they were running in the street, trying to avoid the fire. They jumped in the lake,” said Quebec MP and federal Industry Minister Christian Paradis, who was on the ground Saturday.

“It was like what you see in a Hollywood movie. It’s terrible.”

The cause of the derailment was not immediately known. Police said it’s too early to speculate what happened.

According to the company’s website, the railway serves Maine, Vermont, Quebec and New Brunswick and owns more than 800 kilometres of rail tracks.

Looking for missing residents

A number of residents in the town have been reported missing.

Those who can’t get in touch with their loved ones are urged to go to the local high school, where they can meet with investigators.

A Facebook group was quickly set up to help people track down loved ones who couldn't be reached by phone.

“We’re in emergency mode,” Gomez del Prado said. “Trying to reassure the families, trying to get in touch with the people missing.”

A woman who finished her shift at a downtown bar about an hour before the explosions told CTV News she still hasn’t heard from her friends who were in the area.

‘I haven’t heard from any of them,” she said. “I can’t say anything more than that. We’re waiting for confirmation.”

The Red Cross has set up a shelter, where about 200 people had registered by Saturday afternoon.

Damage to town

Police said about 30 buildings in downtown Lac-Megantic have been affected by the fire.

They include the town’s library, pharmacy, a number of stores and a popular bar where locals liked to gather on warm summer nights.

Lac-Megantic resident Claude Bedard told The Canadian Press that the town has never seen anything like the fire.

“It’s terrible,” he said. “The Metro store, Dollarama, everything that was there is gone.”

The disaster also forced the town to shut off the drinking water supply after some crude oil spilled into the nearby Chaudiere River.

Mayor Colette Roy-Laroche said trucks full of potable water have been brought in for the residents.

Offers of help

A number of neighbouring communities, including Sherbrooke and Saint-Georges-de-Beauce, were asked to help Lac-Megantic deal with the fire.

Speaking in Calgary on Saturday, Prime Minister Stephen Harper offered his condolences to those affected by the derailment.

“What has happened is shocking and truly devastating. My thoughts and prayers, and those of all Canadians, are with the people of Lac-Megantic as they deal with this disaster in their community,” he said.

Harper said he has spoken to Quebec Premier Pauline Marois and federal officials are "ready and available" to assist the province as needed.

Harper is expected to tour the region and meet with local officials Sunday.

With reports from CTV’s Montreal Bureau Chief Genevieve Beauchemin, CTV Montreal's Aphrodite Salas and CTVNews.ca's Christina Commisso