A Canadian jury has found three former rail workers not guilty of criminal negligence for their connection to the Lac-Megantic disaster that killed 47 persons five years ago, a media report said.

On July 6, 2013, a runaway train filled with petroleum crude oil derailed in Quebec town when the unattended 74-car freight train carrying Bakken Formation crude oil rolled down a 1.2 per cent grade from Nantes, the BBC said.

It resulted in fire and explosion of multiple tank cars that destroyed more than 30 buildings in the Lac-Megantic town’s centre, roughly half of the downtown area, making it the fourth-deadliest rail accident in Canadian history.

At least 39 of the remaining buildings had to be demolished due to petroleum contamination, initial newspaper reports had described a one-km blast radius.

The trial began on October 2, 2013, in a Quebec Superior Court and locomotive engineer Tom Harding, traffic controller Richard Labrie and manager of train operations Jean Demaitre were charged in 2014 with criminal negligence causing death, the BBC said.

The tragedy began when the fire broke out in the main locomotive after Harding had parked the train in the village of Nantes and left for the night to sleep.

Firefighters extinguished the flames and turned off the engine, which cut the air brakes.

An hour later, the train rolled into downtown Lac-Megantic and derailed, exploding in a huge blaze.

Harding admitted that he only applied seven handbrakes and did not fully test them before leaving the train.

The prosecution argued more handbrakes would have stopped the train from moving.

Under Canada’s criminal code, the charge carries a potential life sentence. All three pleaded not guilty.

The jurors listened to hours of technical testimony from train specialists, heard audio recordings from the incident and listened to former rail employees testify that the company had no budget for training and placed little importance on safety, according to CBC.

The twelve men and women on the jury began deliberating on January 11.

On January 16, Quebec Superior Court Justice Gaetan Dumas sent them back into deliberations after they told him they were at an impasse.

They deliberated for eight days, at one point asking the judge for clarification on “marked difference”, which the behaviour of the accused would have to be noticeably different from a colleague in a similar circumstance.

When the verdict was finally read on Friday, the CBC reported that all those in the courtroom let out a loud gasp.

Lawyers for the accused had argued that many factors were out of their control that contributed to the disaster, including a culture at Montreal, Maine and Atlantic Railway (MMA) of relaxed standards and insufficient training.

MMA also failed to heed a Transportation Safety Board’s report that said the rail line running from Nantes to Lac-Megantic was the second steepest of any stretch of track in Canada, the BBC said.

The Canadian Transportation Agency suspended MMA’s licence after the accident.