The passenger train that derailed west of Toronto, killing three VIA Rail employees, was in the process of switching tracks at the time of the accident, a senior official at the Transportation Safety Board of Canada at the scene told reporters Monday.
The train's event recorder has also been recovered and is being examined by the Transportation Safety Board.
VIA Rail said the victims were two veteran engineers, Ken Simmonds, 56, and Peter Snarr, 52, of Toronto, and a trainee, Patrick Robinson, 40, of Cornwall.
Both engineers were "very experienced," said VIA Rail spokeswoman Michelle Lamarche. Mr. Robinson was on board to observe the other two and familiarize himself. A union official said it is believed it was only the first or second time Mr. Robinson had been riding with the locomotive engineers.
Mr. Snarr was a second-generation railway man, said his brother Alan. As a child, Mr. Snarr already played with locomotives. He worked his way up the ranks, starting as a freight-train brakeman. He had worked as a train engineer since May 1978, first at CN before moving to VIA. Mr. Simmonds started in 1979 and had also worked for both rail companies. He leaves behind two grown daughters.
The accident injured 45 people after the locomotive and the five cars went off the tracks Sunday afternoon, flipping one car and sending passengers flying into the air. By Monday morning, only eight passengers remained in hospital, in stable conditions.
Tom Griffith, the lead investigator in the probe, said it's too early to speculate on the cause of the crash, but promised the board will look into every possible factor, including speed.
"The download (from the event recorder) will tell us exactly what was happening, what the crew was doing on that locomotive," he said at the scene.
"It will tell us the speed, it will tell us the brake pressure, tell us when the brakes were applied, whether he was blowing the whistle," he said.
Former VIA engineer Daniel Christie speculated after looking at video from the scene that the collision had something to do with the location on the tracks, just below a signal mast, which works like a traffic light. Below, he said, is where the tracks switch over.
"Something happened at that location," he said, adding it's where trains can change direction. "It's a crucial location."
After touring the scene of the derailment on Monday, VIA Rail president and CEO Marc Laliberté offered condolences to the families of his employees who were killed, and wished those injured a speedy recovery.
"This tragic accident touches us very deeply," he said.
But he also sought to reassure members of the public who might become fearful of travelling by train.
"I said, oh my God, this is really serious. I never, in 30 years of service in the industry, lost an employee," he told reporters. "Despite this very tragic accident, I can assure you that rail travel is still a very safe way to travel."
Mr. Laliberté said he plans to speak to the families of those killed this afternoon. He also said VIA has yet to estimate the cost of the accident, "but it's not important at this stage."
It might take a couple of days before service on the tracks returns to normal, Mr. Laliberté added, but they will not reopen today.
Earlier on Monday morning, regional commuters in Burlington who normally board the GO Train service at nearby Aldershot crammed into buses as the station remained closed.
GO put on shuttle buses so passengers could bypass the crash site and commuters arriving in downtown Toronto from the West reported a crowded but smooth trip into the city.
"Everyone from Aldershot was redirected to Burlington station," said Kevin Youkhana, a web developer who gets on at Appleby. "It was really packed, packed in like sardines."
Many commuters said that the delays they expected did not occur.
"Maybe a lot of people stayed home," said one man as he rushed past at Union Station. "They have a great excuse."
Passengers travelling in southwestern Ontario can check on the status of their train at 1-888-VIA-RAIL or at viarail.ca.
York University student Josh Dykstra was in the train when it tilted onto its side and slammed into the ground. Bodies, knapsacks and plastic bottles launched forward, while the railroad car's roof was partially peeled open by a nearby building.
"People were airborne, flying two or three rows forward," said Mr. Dykstra.
All three deceased were in the locomotive at the front of the train. The next two cars made up the bulk of the carnage, where passengers were trapped inside for as long as an hour while paramedics dealt with priority patients.
The locomotive and the five cars went off the tracks at about 3:30 p.m., leaving one car completely on its side. In Mr. Dykstra's car, the first passenger car on Toronto-bound train 92, on its way from Niagara Falls, he said one passenger flew back-first into one of the windows, and an elderly woman gushed blood from a deep cut on her forehead.
How the train managed to slide off the track remains a mystery, said VIA's chief operating officer John Marginson.
In 2008, about 19 freight cars were derailed in an accident eerily close to Sunday's fatal crash. At a press conference, Burlington Mayor Rick Goldring said the 2008 accident took place about 100 metres from Sunday's crash site – but authorities reiterated that they have no evidence the two are connected.
Like almost all of VIA's passenger trains, this one was a rebuilt model and it had been reconstructed more than a year ago – a duration of time that suggests this was not a factor in the crash, Mr. Marginson said. Worries about a fuel leak were ruled out hours after the crash, he added.
The most serious injuries were a heart attack, a back fracture and a broken leg, Mr. Marginson said. All of the passengers in the two flipped railway cars were evacuated within 90 minutes of the crash. Firefighters used metal-piercing equipment, as well as ladders to climb through broken windows, to access the victims.
Two Ornge air ambulances were called at about 4 p.m., both arriving roughly 10 minutes later.
The victims were taken to at least four hospitals, with the most serious being taken to Hamilton Health Sciences. For several hours the hospital was placed into "Code Orange," the response for external disasters.
"It's not something that happens frequently by any means," said spokeswoman Jennifer Kramer.
Hospitals and emergency workers from Toronto were involved as well, sending a hospital bus and a superintendent to the scene and taking 10 patients with minor injuries to a hospital in Mississauga.
Deanna Villella, 40, said that in the moment before the train flipped on its side, it felt like the train had switched tracks – except her car just kept drifting sideways.
Realizing the car was about to tip, she reverted to the instructions she had heard so many times on plane rides and stuck her head between her legs. When the car flipped, she held herself in her chair, suspended above the ground, unsure of what had happened. "I just knew I needed to keep my head down," said Ms. Villella who was on her way to Gananoque, Ont., for a conference.
Many passengers squeezed out of the train through holes that had been created in the crash. In a press release, VIA said there were a total of 75 passengers on board.
The force of the crash was felt in homes and stores nearby. Dave Deyell was eating in the restaurant at a nearby IKEA when he thought he was in the middle of a small earthquake. "You could feel it," he said.
With a file from James Bradshaw and reports from Canadian Press