Media playback is unsupported on your device Media caption Eyewitnesses say the streets "were filled with fire"

Police have said they expect more people to be found dead after a runaway train carrying light crude oil exploded in the Canadian town of Lac-Megantic.

The blast sent a fireball and black smoke into the air, killing one and forcing the evacuation of 1,000 people.

Dozens of buildings were destroyed in the town, about 250km (155 miles) east of Montreal.

They include a bar full of customers. Police are trying to account for dozens of missing people.

The train's cars reportedly uncoupled from a parked engine and derailed early on Saturday.

Rail company officials said the train had been immobilised in a neighbouring village before a scheduled crew change, but for an unknown reason had then started rolling downhill into Lac-Megantic.

Eyewitnesses said that by the time the driverless train reached the town it was travelling at considerable speed.

'Like a movie'

The search for more bodies is expected to continue at dawn.

Local media have reported up to 100 people missing.

"We have already confirmed one death and we expect there will be others," said police spokesman Guy Lapointe.

"We also expect that the number of people reported missing will be greater than the final death toll."

He said some people had been reported missing several times by different family members.

Some 120 firefighters have been fighting the blaze, which has continued for more than 24 hours.

Firefighters from across the border in the US are assisting.

Eyewitnesses reported that the town centre - where there are a number of bars - was crowded at the time of the blast, and that "chaos" ensued.

Image caption Firefighters fought the blaze for more than 24 hours

Bernard Theberge, who was on the patio of the Musi-Cafe at the time, said he was lucky to escape and feared for those inside the bar.

"It was like a movie," he said, quoted by the Associated Press news agency. "Explosions as if it were scripted - but this was live."

A woman described how close she was to one of the wagons.

"There were some sparks, and the car lifted and came to lie on its side in front of me, but I turned around and ran without stopping," she told the CBC TV.

Brakes 'tight'

The Montreal, Maine & Atlantic train had five locomotive engines and 73 cars filled with light crude oil, and was parked in the village of Nantes - about 7km (four miles) from Lac-Megantic - during an overnight driver shift-change, a company spokesman told Canada's La Presse newspaper.

The railway's chairman, Edward Burhardt, quoted by CBC, said an engineer had parked the train and put the brakes on "properly" before going to a local hotel for the night.

The cars filled with fuel somehow became uncoupled, causing them to roll downhill into the town and derail, said the spokesman, Joe McGonigle.

Media playback is unsupported on your device Media caption Canadian PM Stephen Harper: "What has happened is shocking and truly devastating"

"It seems that the brakes were tight on locomotives," Mr McGonigle told La Presse. "We found the locomotives higher up, half a mile (800m) away."

Some of the cars exploded, creating a massive fireball and setting fire to nearby homes and businesses.

A one-kilometre exclusion zone was set up amid fears of more pressurised containers exploding.

"When you see the centre of your town almost destroyed, you'll understand that we're asking ourselves how we are going to get through this event," an emotional Mayor Colette Roy-Laroche told a televised news briefing.

Prime Minister Stephen Harper said in a statement: "Our thoughts and prayers go out to the families and friends of those affected by this morning's tragic train derailment and subsequent fires in Lac-Megantic, Quebec.

Some of the train's cargo spilled into the nearby Chaudiere river, said Environment Quebec spokesman Christian Blanchette, adding that communities downstream of Lac-Megantic had been warned to take care if using river water.

A mobile laboratory had been set up to monitor the quality of the air, he added.

The train was carrying the crude oil from the Bakken Field in North Dakota. Montreal, Maine & Atlantic owns more than 800km (500 miles) of track serving Maine, Vermont, Quebec and New Brunswick.

A lakeside town that is home to some 6,000 people, Lac-Megantic is close to the US border with Vermont and 210 km (130 miles) north of Maine's capital, Augusta.