quebec explosion
© Reuters/Surete du QuebecSmoke billows from a fire at the site of a train derailment in Lac Megantic, Quebec in this July 6, 2013 aerial handout photo
Four tanker cars of petroleum exploded in the east Canadian province of Quebec after a train derailed, leaving flames billowing hundreds of feet into the sky. Some 30 buildings were destroyed and 1,000 evacuated from homes. At least one has been killed.

"It's dreadful," Lac-Megantic resident Claude Bedard told the Canadian Broadcasting Corporation. "It's terrible. We've never seen anything like it. The Metro store, Dollarama, everything that was there is gone."

quebec explosion 1
© Reuters/Mathieu BelangerA burning train wagon is seen after an explosion at Lac Megantic, Quebec, July 6, 2013
The 73-tanker train left the tracks shortly after 1 a.m. local time as it was passing through the French-speaking lakeside town of Lac-Megantic, causing a huge fireball to rise into the night sky. Witnesses told Reuters they heard at least five loud blasts. The fire spread to a number of homes.

Radio Canada has reported that dozens are missing.

The blast was described as "like an atomic bomb," by a local restaurant owner. Bernard Demers had to evacuate the premises, telling AP that everybody had been terrified.

The train "somehow got released," and had no conductor on board, according to the rail company. The convoy of crude oil left the station of its own accord during a shift change in Nantes, west of the affected region.

"We're not sure what happened, but the engineer did everything by the book. He had parked the train and was waiting for his relief," Montreal, Maine and Atlantic Railway, Inc Vice President Joseph McGonigle said on Saturday.

Approximately 1,000 of the town's 6,000 residents have been evacuated, with many missing. Police imposed a 1/2-mile (1-km) security zone around the blast's center.

Early on Saturday, a Quebec provincial police Lt., Michel Brunet, told a press briefing that it had been too early to say if there were any casualties.

"I can say absolutely nothing about victims...we've been told about people who are not answering their phones, but you have to understand that there are people who are out of town and on holiday," said Brunet.

"Thoughts & prayers are with those impacted in Lac Megantic. Horrible news," tweeted Prime Minister Stephen Harper as firemen tried to calm the blaze.