At least 53 migrants were killed Thursday in Mexico after the truck they were hiding in hit a retaining wall and overturned in the southern state of Chiapas, a major transit point for those trying to reach the United States.

Another 58 people also were hurt, three of them seriously, according to a preliminary report from the prosecutors in Chiapas, which borders Guatemala.

"So far, 53 people have died and three more are seriously injured," the office said in a statement which also announced it was taking over the investigation of the incident. 

The migrants were crammed into the truck, civil protection officials told reporters.

"According to the statements of the survivors, most of them are from Guatemala," said Luis Manuel García, the Civil Protection director for Chiapas.

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.

Bodies were wrapped in white sheets or other blankets.

State Governor Rutilio Escandon said the injured should get "prompt attention and assistance," adding: "Law enforcement will determine who is responsible." 

Guatemalan President Alejandro Giammattei pledged to provide any of his countrymen with consular assistance, including help in getting back home, in a message on Twitter.

His Mexican counterpart Andres Manuel Lopez Obrador offered his condolences on Twitter, calling the incident "very painful."

The National Migration Institute, a department of the interior ministry, said in a statement that "humanitarian visitor cards" would be offered to survivors, in addition to humanitarian aid such as food and accommodation. 

The INM will coordinate with local and federal authorities efforts "to provide consular assistance, identify bodies, cover funeral costs," it said.

- Finding a way north -

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. 

Other migrants have opted to join the so-called caravans, in which people travel much of the long journey on foot, subject to extreme weather in many regions of Mexico and the threat of drug cartels and other organized crime syndicates. 

The Mexican branch of the UN refugee agency (UNHCR) has called for "alternatives" and legal pathways for migration in order to "avoid tragedies like this one."

And Mexican immigration authorities said the survivors could be offered temporary permits to remain in the country for "humanitarian reasons" along with food and housing aid.

The flow of undocumented migrants, who are fleeing violence and poverty in their home countries -- mainly in Central America -- has grown since President Joe Biden came to office with a promise to scrap the hardline border policies of his predecessor Donald Trump. 

More than 190,000 migrants were detected by Mexican authorities between January and September, three times more than in 2020. Some 74,300 have been deported.