CANADIAN PRESS UPDATE: Authorities in Quebec say two more people are confirmed dead in the train derailment and massive fire in Lac-Megantic to bring the declared death toll to five.
Police also say about 40 people are considered missing.
LAC-MEGANTIC, Que. -- At least one person was declared dead Saturday after explosions destroyed the heart of a Quebec town and sent spectacular fireballs dozens of metres into the sky after a train transporting crude oil came off the tracks.
"Our investigators are trying to track down family members, so we can't give the identity of this person, but at this time we can confirm one person has died,'' provincial police Lt. Michel Brunet told a news conference.
Brunet refused to say how many others might be dead in Lac-Megantic but said authorities have been told "many'' people have been reported missing.
Up to 1,000 people were forced from their homes in the middle of the night in the town, which is about 250 kilometres east of Montreal.
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Witnesses said the eruptions sent many locals scrambling through the streets under the intense heat of towering fireballs and a red glow that illuminated the night sky.
The tanker rail cars exploded in the downtown core, a popular area known for its bars and that is often bustling on summer weekend nights. It's also a district that many here called home.
Dozens of locals gathered at the edge of a wide security perimeter Saturday and many feared the worst.
"On a beautiful evening like this with the bar, there were a lot of people there,'' said Bernard Demers, who owns a restaurant near the blast site in the town of about 6,000.
"It was a big explosion. It's a catastrophe. It's terrible for the population.''
Flames and billowing black smoke could be seen more than 12 hours hours after the derailment, which involved the 73-car train. Police say the first explosion tore through the town shortly after 1 a.m.
Dozens of residents stood on the main drag leading into the downtown area, hours after the explosions. Many locals had been awake much of the night, after the area shook from blasts that one man initially thought was a ``nuclear'' bomb and shot flames higher than the steeple of a nearby church.
They stared down the straight street from behind the orange tape. Less than a kilometre down Rue Laval a railway tanker sat at the edge of the road as flames danced around it.
Firefighters could be seen dousing the blaze for hours.
Demers, whose home was evacuated, described the scene in town overnight.
"Early this morning (there was) a big explosion like an atomic bomb,'' he said in an interview. "It was very hot.... Everybody was afraid.''
Demers has lived in Lac-Megantic for 45 years.
"Everybody is very friendly... It's like a small village,'' he said.
"A beautiful town but now it won't be the same.''
Charles Coue said he and his wife awoke to the explosion, which went off a couple of hundred metres from their home.
"(We felt) the heat,'' said Coue, who sprinted from his house with his wife amid the panic.
"It went boom and it came like a fireball.''
A Facebook group was quickly set up to help people track down loved ones who couldn't be reached by phone.
A woman offering to locate people at an emergency centre set up at the local high school received hundreds of requests for help.
Lac-Megantic resident Claude Bedard described the scene of the explosions as "dreadful.''
"It's terrible,'' Bedard said. ``We've never seen anything like it. The Metro store, Dollarama, everything that was there is gone.''
Some of the train's 73 cars exploded and the fire, which could be seen for several kilometres, spread to a number of homes.
"The flames in the sky were really impressive,'' said resident Pierre Lebeau.
A large but undetermined amount of fuel also spilled into the Chaudiere River.
Several neighbouring municipalities, including Sherbrooke and Saint-Georges-de-Beauce, were enlisted to help Lac-Megantic deal with the disaster.
Emergency services south of the border were also lending a hand.
A fleet of fire trucks were deployed from northern Maine, according to a spokesman at the sheriff's office in Franklin County.
The train belongs to Montreal Maine & Atlantic, which says on its website that it owns more than 800 kilometres of track serving Maine, Vermont, Quebec and New Brunswick.
A senior executive with the company was quoted in various media on Saturday as saying there was no conductor in the train when it started moving by itself after the conductor had locked the brakes.
Environment Quebec spokesman Christian Blanchette said the 73 cars were filled with crude oil and that four were damaged by fire and the explosions.
"Right now, there is big smoke in the air, so we have a mobile laboratory here to monitor the quality of the air,'' Blanchette said in an interview.
"We also have a spill on the lake and the river that is concerning us. We have advised the local municipalities downstream to be careful if they take their water from the Chaudiere River.''
Prime Minister Stephen Harper expressed his sympathy 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,'' Harper said.
"We hope evacuees can return to their homes safely and quickly. The people of Lac-Megantic and surrounding areas can rest assured that our government is monitoring the situation and we stand by ready to provide any assistance requested by the province.''
Liberal Leader Justin Trudeau also commented on the events.
"My thoughts are with all the families who have had to be evacuated, and especially with all those who are searching for their loved ones,'' said Trudeau.
The explosions attracted worldwide media coverage, with the story trending as the most popular international story on the BBC's website as well as featuring on other sites including Le Monde's.