The center of Lac-Megantic, a lakeside town of 6,000, was still cordoned off on Monday morning as police struggled to find the remains of people who likely died.
Police said they had been unable to examine much of the town center overnight because the area was still too dangerous. Dozens of rail tanker wagons, some of them destroyed, were sprawled around the accident site.
"It's an area that is still extremely risky... The fire service decided they could not allow us to go there for security reasons. We'll see what we can do today," police spokesman Benoit Richard told reporters on Monday.