Mexican authorities said the truck was smuggling migrants trying to make it to the United States. It was the highest number of migrant deaths in Mexico since 2010, when 72 migrants were killed by a drug gang.
By Friday, the Mexican government said 54 people died. At least 50 others were hurt, but some injured people ran away because they were worried about being arrested.
Most of the people were from Guatemala, but some were from Honduras, Mexico and Ecuador.
Rescuers worked to help those still alive out of the truck. The dead were moved to the side of the road in Tuxtla Gutierrez, a city in the Mexican state of Chiapas.
The cargo area of the truck was destroyed. People said the truck fell on its side and hit the bridge. Officials said the driver may have been going too fast and lost control at a curve in the road.
Luis Manuel Moreno of the Chiapas civil defense office said more than 20 survivors had serious injuries.
Guatemalan Celso Pacheco was in the truck. He said the driver was going too fast and lost control. The head of Mexico’s National Guard said the driver ran away.
Another man said “the trailer couldn’t handle the weight of the people."
International leaders expressed their concern about the deaths and injuries.
Ken Salazar, the U.S. ambassador to Mexico, said in a Twitter post: “human smugglers disregard human life for their own profit” and told people not to migrate outside of the normal rules.
Thousands of people travel through Mexico each month with the hope of reaching the U.S.
In recent months, Mexico has tried to stop large groups from walking toward the border. Many, now, are trying to make it in less visible ways.
In October, Mexican authorities stopped six trucks in the state of Tamaulipas and found over 600 people inside.
Irineo Mujica is an activist. He is walking with a group of about 400 migrants through Mexico. He blamed immigration policies for the tragedy.
The injured migrants will be able to stay in Mexico during their treatment because they are witnesses to a crime. Mexico’s National Immigration Institute said it would give visas to the survivors.
The Mexican government said it would work to identify the dead and cover their burial costs or the cost of sending their bodies home.
Mexican president Andres Manuel Lopez Obrador called the crash “very painful” on Twitter.
I’m Dan Friedell.