At least 49 people have been killed and dozens more injured after the truck they were being transported in crashed in southern Mexico, authorities say.

Iran PressAmerica: A cargo truck jammed with people who appeared to be Central American migrants rolled over and crashed into a pedestrian bridge over on a highway in southern Mexico on Thursday, killing at least 49 people and injuring nearly five dozen others, authorities reported.

At least 58 people have been taken to hospital with injuries, said Luis Manuel Garcia, head of the Chiapas civil protection agency.

He said the victims included men, women and children. Most of the people in the trailer were migrants from Honduras, the local fire brigade chief told Reuters news agency.

Officials said it appeared that the driver was speeding when he lost control of the vehicle on the highway connecting the city of Chiapa de Corzo with the state capital Tuxtla Gutierrez. He later fled the scene.

Local television images showed large numbers of ambulances, firefighters and rescue workers gathered around the crashed vehicle, together with some confused and shocked migrants who were awaiting medical attention.

Moving undocumented migrants hidden in trucks is the most common method used by human traffickers operating along the border from Guatemala into Mexico. They then head north to the US border.