Story highlights Engine shutdown, air brake release may have caused train derailment, rail company says

Train rolled downhill, derailed and exploded into flames

At least five people killed; about 40 unaccounted for

"It looks like a war zone here," Prime Minister Stephen Harper says

The company responsible for a runaway train that exploded in a small Canadian town Saturday said an engine shutdown may have released air brakes holding the train in place.

At least five people are dead and around 40 are unaccounted for in Lac-Megantic, Quebec, after a 73-car train carrying crude oil derailed and crashed, local law enforcement officials said. Tankers exploded, sending thick plumes of smoke into the night sky, leveling dozens of homes and buildings and forcing nearly 2,000 people from their homes.

The train had stopped for a crew change Friday night in a station about seven miles from Lac-Megantic, the Montreal, Maine & Atlantic Railway said in a statement. The train's engineer had "tied down" and checked into a motel.

"One fact that has emerged is the locomotive of the oil train parked at Nantes station was shut down subsequent to the departure of the engineer who had handled the train from Farnham, which may have resulted in the release of air brakes on the locomotive that was holding the train in place," the company said in a statement, noting that it still didn't have "complete information."

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The explosion devastated the small lakeside town, where firefighters were still working Sunday to contain hot spots so law enforcement could expand its investigation. Investigators with the Transportation Safety Board of Canada found the locomotive event recorder and planned to analyze it for information on throttle position and speed, among other data.

The burned bodies of the dead have been sent to Montreal for identification, but "we know that there will be many more" deaths, police spokesman Lt. Michel Brunet said Sunday.

Canadian Prime Minister Stephen Harper likened the town to a "war zone" after touring it Sunday.

"There is not a family in this area that is not touched by this," he said in a press conference outside Polyvalente Montignac High School, the main staging area for recovery efforts.

"A beautiful downtown here has been destroyed," he said. "There's going to be a need for substantial reconstruction."

Harper would not comment on specifics of the disaster except that he expected information "about why this occurred" to lead to a police investigation.

"I've heard things that concern me greatly," he said. "There will be investigations that will point to guilty or responsible people."

Witnesses told the CBC they heard five or six explosions. One person saw the first train tanker tip over and yelled "run, run!" as he dashed toward the lake for which the town is named. He told CBC the flames chased him to the edge of the water.

"The fire was moving so quickly," he said. "We saw balls of fire shooting out onto the water."

One woman told CNN affiliate CTV she was working at a bar nearby and got off work an hour before the accident.

"I have no news from my friends; I haven't heard from any of them," she told tearfully told CTV. "I can't say more than that. We're waiting for confirmation."

Amid the chaos, friends and families are scrambling to find their loved ones.

More than 17,000 people have joined a Facebook page to help people connect with their loved ones in the town . Locals and outsiders have posted desperate notes to try to figure out where their friends and family were on the night of the crash.

Some posts bring relief -- "Mom it is alisun and oceannie and rosaly we are all alive I love you," one reads in French.

Others look less promising.

Multiple posts ask about Guy Bolduc, a singer who was performing at Musi-Cafe in town.

"All of his fans, all over Quebec, but also his fellow singers (of whom I am one) hope to see him again alive!!! Come on my GuyBol, come out of your hiding place," one member wrote.

The group administrators ask that members not post about deaths until they're confirmed.

Residents told the CBC they have never seen anything like it.

"It's dreadful," Claude Bedard said. "It's terrible. The Metro store, Dollarama, everything that was there is gone."

Authorities evacuated more than a third of the town of 6,000 people, most from the center of the town and a home for the elderly.

As authorities worked to get more details, residents of the scenic town grappled with the loss.

"It's like the town has been cut by a knife," Sgt. Gregory Gomez del Prado told the CBC.

Resident Amanda Gabrielle said the train crashed on her birthday. She lost her dog, she's now homeless, and she doesn't have any family or friends.

"I lost everything," Gabrielle told the CBC. "I don't know what's going to happen to me."

For information on missing people, call 1-800-659-4264.