There was virtually no chance of survival for three engineers who were killed when the train they were travelling in flew off the tracks and collided with a building on Sunday in Burlington, Ont., said the lead investigator from the Transportation Safety Board.

In addition to the three Via Rail employees who were killed, 46 others were injured. Nine were still in hospital on Monday morning, some with serious injuries.

Tom Griffith, the Transportation Safety Board's investigator-in-charge, told a news conference Monday that the impact of the crash was devastating for the engineers.

"They were in the locomotive cab and the locomotive actually turned on its side and struck a building and it destroyed the locomotive cab that the three of them were in," Griffith said.

When asked by a reporter whether the men had any chance of survival, he said "no."

Via Rail has identified the three engineers as longtime employees Peter Snarr and Ken Simmonds, and engineer-in-training Patrick Robinson.

Snarr, 52, and Simmonds, 56, were both from the Toronto area and both had more than 30 years experience as engineers with Via Rail and CN.

Forty-year-old Robinson, of Cornwall, Ont., was a new employee at Via Rail and was observing the engineers as part of his training program.

Griffith said it isn't clear which engineer was at the controls when the accident took place. Robinson could have been driving the train, but only under the supervision of the more experienced engineers, he said.

He also confirmed the train was switching from one track to another when the accident happened.

Investigators recovered the black box from the train on Monday.

Griffith said the all-important recording device was removed from the train in damaged condition, but investigators expect it will still provide vital information about what happened in the moments before the crash.

"The speed, brake pressure, whether the brakes were put on, whether they were blowing the whistle -- it will tell us everything that was going on with that locomotive," Griffiths said.

However, the black box does not include a voice recorder, so investigators will likely be unable to determine what was being said by engineers just before the crash.

He said tracks in the area are in good condition, and although a crew was working near the accident on Sunday, they didn't play a role in the crash.

Griffith said to his knowledge, the engineers made no emergency radio calls in the moments before the accident.

Marc Laliberte, president and CEO of Via Rail, visited the crash site Monday. He said the company was devastated by the loss.

"I'm shocked. These are the things we don't want to see happen," he told reporters. "It's a tragic accident."

He said it was too early to speculate on the cause of the crash and Via has launched an investigation and is working with the Transportation Safety Board and Transport Canada to figure out what went wrong.

"Rail service remains a very, very safe mode of transportation," he said.

The derailment occurred around 3:30 p.m. in an industrial area near Aldershot station, about 60 kilometres west of Toronto. The train was reportedly switching lines at the time of the accident. One of the six derailed train cars crashed into a small building near the train tracks, flipping on its side.

Via train 92 was travelling eastbound from Niagara Falls to Toronto with 75 passengers and four crew members on board.

About 60 passengers were initially trapped in the wreckage, as dozens of police officers, firefighters and paramedics worked frantically to free them. Some were carried away on stretchers while others walked away shaken, but unharmed.

On Monday, Halton Regional Police said they were looking for about 12 passengers who left the scene of the accident, most likely by private transportation. They asked any passengers who left the crash scene without speaking to police to contact them.

By 6:30 p.m., everyone was out of the train and all passengers had received some type of medical attention, Via Rail spokesperson Michelle Lamarche said.

One passenger described feeling a slight bump, followed by immediate chaos as the train derailed and terrified passengers began scrambling to find a way out of the train. One person described it as a "war zone."

Burlington Mayor Rick Goldring said he was at home relaxing with his wife on Sunday night when he got a call letting him know about the deadly accident.

He confirmed another accident occurred in roughly the same area four years ago when a freight train crashed, but said it was too early to speculate whether there was any connection between the incidents.

"Obviously there is going to be some questions around that and I can't speculate as to any relationship between what happened four years ago and last night. I'm sure they inevitably will be looking at that," he told Canada AM from the crash site.

Goldring said it was a top priority to clear the tracks Monday morning to allow traffic to resume on what he said is one of the busiest rail routes in Canada.