The train, which had been parked overnight at the top of a nearby hill, came barrelling into the lakeside town at speed after its brakes apparently failed, sparking at least six massive explosions as it derailed.
Witnesses to the crash, which forced a third of Lac-Megantic's 6,000 residents to evacuate their homes, said the town centre resembled a warzone, with at least 30 buildings destroyed. Some spoke of fleeing floods of burning crude oil that spilled through the streets.
So fierce were the flames around the scene of the crash that rescue workers were unable to go near for much of yesterday, with a search for bodies due to begin on Sunday at dawn.
While only three fatalities had been confirmed as of Sunday morning, officials said that up to 80 people were still believed to be missing in the crash zone.
One firefighter, who asked to remain anonymous, said that at least 50 of them were thought to have been in the Musi-Cafe, which was just ten yards from the crash scene and had been consumed by the flames. “There is nothing left,” he said.
Bernard Théberge, 44, who was smoking a cigarette outside the cafe, told how he fled just in time after hearing the sound of the approaching train and realising that it was about to crash.
“It was going way too fast,” Mr Théberge told the Globe and Mail newspaper. "I saw a wall of fire go up. People got up on the outside patio. I grabbed my bike, which was just on the railing of the terrasse. I started pedalling and then I stopped and turned around.
I saw that there were all those people inside and I knew right away that it would be impossible for them to get out." Mr Théberge, who said he owed his own survival to being outside at the time, added: "There were maybe 60 people inside. This is a first. Smoking saved my life."
The cause of the crash was still unknown, but a spokesman for the Montreal Maine & Atlantic company, Christophe Journet, told the AFP news agency that the train had been stopped in the neighbouring town of Nantes, around 8 miles west of Lac-Megantic, for a crew changeover.
For an unknown reason, Mr Journet said, the train “started to advance, to move down the slope leading to Lac-Megantic,” even though the brakes were engaged.
As a result, “there was no conductor on board” when the train crashed, he said. 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.”
The train’s engine was found about one kilometre from where the explosions took place. But Edward Burkhardt, the president of Rail World Inc., the parent company of Montreal, Maine & Atlantic Railway, said he could not yet understand how the train had got away.
“If brakes aren’t properly applied on a train, it’s going to run away,” he said. “But we think the brakes were properly applied on this train.” One witness, Nancy Cameron, posted a photo on social media websites showing one of the train’s locomotives spouting flames near Nantes.
Firefighters had apparently also been called to a fire on the same train a few hours before the derailment. Another eyewitness, Yvon Rosa, said he had just left the Musi-Cafe when he saw the train speeding into the middle of the town.
"I have never seen a train traveling that quickly into the center of Lac-Megantic," he told Radio-Canada. "I saw the wagons come off the tracks … everything exploded. In just one minute the centre of the town was covered in fire."
A team of investigators from Canada’s transportation safety agency is now investigating. The train consisted of five locomotives and 77 rail cars and was carrying oil from the US state of North Dakota. Lac-Megantic lies in the French-speaking province of Quebec, and is close to the US border. Fires were still burning more than 24 hours after the crash, creating a red glow that illuminated the night sky.
Lines of tall trees in the area looked like giant standing matchsticks, blackened from bottom to tip. Bernard Demers, who owns a restaurant near the blast site, said the explosion was "like an atomic bomb. It was very hot. … Everybody was afraid."
Canada's prime minister, Stephen Harper, offered his “thoughts and prayers” to the town and said the federal government was ready to provide assistance. The local mayor, Colette Roy-Laroche told a televised news briefing.
"When you see the center of your town almost destroyed, you'll understand that we're asking ourselves how we are going to get through this event."
Michel Brunet, a spokesman for Quebec’s provincial police, said late on Saturday that the official death toll remained at one but added: “We expect there will be more fatalities." At one emergency tent yesterday, paramedics sat idly in the torrid heat with no one to help. Residents gathered to await news of survivors, which never came.
Relatives in the tourist town of 6,000 full-time residents were already starting to grieve. Michel Brunet, a spokesman for Quebec’s provincial police, said late Saturday the official death toll remained at one but added: “We expect there will be more fatalities.”
Today, the cafe's Facebook page carried messages of condolence and desperate appeals from friends and relatives looking for looking for loved ones on the missing list. "Everybody who didn’t make it back is dead," predicted Frédérique Mailloux, 38, who said six of her friends were missing.
“I have cried every tear in my body.” At a community centre, Jacques Bolduc and Solange Gaudreault emerged after providing a DNA sample to potentially identify their son, Guy Bolduc, a 23-year-old singer who was performing at the Musi-Cafe.
“Our boy wanted so much to live,” Mr. Bolduc told Radio-Canada. “The police told us there is no hope.” Nearly two square kilometres of the downtown were razed, said local fire chief Denis Lauzon.
“The scene is like one you see after a big forest fire. There are only parts of the buildings left, trees have been completely burnt, there is no grass left, the cars are charred. This is total destruction.”