Canadian police have opened a criminal investigation into the runaway oil train crash in a small Quebec town as the death toll climbs to 15, with dozens more people still missing.
Police say more bodies could be buried in the burned-out ruins.
Quebec police inspector Michel Forget said that investigators have "discovered elements" that have led to a criminal probe in the small town of Lac-Megantic.
He didn't go into detail but ruled out terrorism, saying police are more likely to explore the possibility of criminal negligence. Provincial police spokesman Sergeant Benoit Richard said no arrests have been made.
The death toll rose again with the discovery of two more bodies on Tuesday, and 35 people are still missing. The bodies that have been recovered were burned so badly they have yet to be identified.
Investigators are focusing on whether a fire on the train a few hours before the disaster set off a chain of events that resulted in the explosion, raising questions about the safety of transporting oil by rail instead of pipeline.
The unmanned Montreal, Maine & Atlantic Railway train broke loose early on Saturday and sped downhill in the darkness nearly seven miles before jumping the tracks at 63 mph. All but one of the 73 cars were carrying oil. At least five exploded.
The local Transportation Safety Board said there had been no warning of the runaway train because staff had been unaware of it. Warning systems are not in place on secondary rail lines, said TSB manager Ed Belkaloul.
The derailment and explosions destroyed about 30 buildings, including a crowded bar, and forced about a third of the town's 6,000 residents from their homes.
The same train had caught fire hours earlier in a nearby town, and the engine was shut down - standard operating procedure dictated by the train's owners, Nantes Fire Chief Patrick Lambert said.
Edward Burkhardt, president of the railway's US-based parent company, Rail World, suggested that shutting off the locomotive to put out the fire might have disabled the brakes.
"An hour or so after the locomotive was shut down, the train rolled away," he told the Canadian Broadcasting Corporation.
Transportation Safety Board investigator Donald Ross said the locomotive's black box has been recovered but warned that the investigation was still in its early stages.
Efforts are continuing to stop waves of crude oil spilled in the disaster from reaching the St Lawrence River, which supplies water to the province.