Several people were missing after four tank cars of petroleum products exploded in the middle of a small town in the Canadian province of Quebec early yesterday in a fiery blast that destroyed dozens of buildings.

The disaster occurred shortly after 7am when a freight train derailed in Lac-Megantic, a picturesque lakeside town of about 6,000 people near the border with Maine. Although police said they could not yet get close enough to determine whether there were any casualties from the still-burning fires, an aerial photograph showed widespread devastation in the town centre.

French-language broadcaster Radio-Canada said one building at the centre of town was a bar popular with young people. An eyewitness told the broadcaster the town center had been crowded at the time of the derailment.

“Many parents are worried because they haven’t been able to communicate with a member of their family or an acquaintance,” Mayor Colette Roy-Laroche told the channel.

“We can’t give out any information on what’s happening right now because the firemen haven’t been able to get close.”

The Canadian Broadcasting Corp. said four pressurized tank cars blew up after the train, which had 73 cars in all, came off the rails. Pictures taken in the moments after the disaster showed a gigantic fireball rising high into the night sky. Residents told reporters they had heard five or six large blasts.

Nearly 10 hours after the derailment, one rail car was still burning.

Fire officials said they feared more of the tanker cars were at risk of exploding. Around 30 buildings in the town center were destroyed, some by the initial blast and others by the subsequent fire, they said.

Police imposed a one-kilometre security zone around the blast and evacuated about 1,000 people from their homes.

“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,” a tearful Roy-Laroche told a televised news briefing.

Prime Minister Stephen Harper made an initial statement via Twitter: “Thoughts & prayers are with those impacted in Lac Megantic. Horrible news.”

Lac-Megantic is part of Quebec’s Eastern Townships region, an area popular with tourists that is close to the border with Maine and Vermont. Quebec is a predominantly French-speaking province in the eastern half of Canada.

Huge clouds of thick black smoke were still rising from the centre of Lac-Megantic several hours after the disaster.

Fire officials said they had asked for help from fire services in the US. Around 20 fire engines were fighting the blaze.

Police said some cars had spilled their contents into the river that runs through the town.