A judge is urging jurors in a criminal negligence trial stemming from a 2013 derailment that killed 47 people in Quebec to try once more to reach unanimous verdicts after they told him they had come to an impasse.

Quebec Superior Court Justice Gaetan Dumas told the eight men and four women Tuesday that failing to reach verdicts for the three defendants will not reflect badly on them, provided they "made an honest effort."

It is the sixth day of deliberations.

A runaway train carrying crude oil from North Dakota derailed in Lac-Megantic and exploded on July 6, 2013. Engineer Tom Harding and former colleagues Richard Labrie and Jean Demaitre are each facing one count of criminal negligence causing the death of 47 people. They have pleaded not guilty.