Deadly Mexico train derailment blamed on stolen nails
Local officials in the southern Mexican state of Tabasco have blamed missing nails in the track for a train derailment which has killed at least six people.
Public Security Minister for Tabasco state Audomaro Martinez Zapata said thieves had "ransacked" the tracks of their nails and metal plaques.
Eight of the cargo train's 12 carriages came off the tracks on Sunday.
Twenty-two people were injured in the accident near Huimanguillo.
Tens of thousands of migrants board the train, known as La Bestia, or the Beast, each year in their attempt to reach the United States in search of better living conditions.
Rescue workers fear more people may still be trapped beneath the carriages.
It is not known exactly how many migrants may have been on the train's roof or clinging to its sides at the time of the accident.
Local residents said they had seen some 200 people climb aboard at a nearby stop.
Hundreds die or lose limbs each year as they fall off the train and get caught under its wheels. Three of the dead in Sunday's accident were Honduran citizens.
Soldiers have been deployed to the remote area to help with the rescue work.
Railway company workers said the tracks had become loose after nails and plaques keeping them in place had been stolen.
Heavy rain further washed away some of the underlying soil, causing the tracks to shift, the workers told local official Andres Dominguez Aguilar.
Tabasco state governor Arturo Nunez said the train's heavy load of scrap metal also may have caused the tracks to sink in the wet ground.
Heavy lifting equipment has been sent to the area to move the overturned carriages.