At least nine and possibly as many as 20 people were seriously injured in the attack late Wednesday near the Veracruz city of Coatzacoalcos, according to various reports. It was unclear whether anyone was killed.
Tomas Gonzalez, a religious lay worker who heads a migrant shelter in the area, said survivors told him that gang members armed with guns and machetes boarded a train they were traveling on and began beating up anyone who refused to pay extortion money equivalent to $100.
Many migrants threw themselves from the moving train to escape the gang, Gonzalez said in a radio interview.
The Veracruz state government confirmed that nine people were injured -- eight Hondurans and one Mexican -- but sought to portray the incident as a brawl among migrants.
"That is a lie," Gonzalez said, noting that the notoriously corrupt government of Veracruz has routinely refused to acknowledge drug gang violence, despite the state's soaring homicide rate.
Another human rights organization said about 300 migrants were assaulted in Wednesday's attack. Mexican media with correspondents in Veracruz put the number injured as high as 20.
It has become common for gunmen from the Zetas drug trafficking network, or affiliates, to extort money from mostly
Thousands go missing every year, according to the Mexican national human rights commission, killed or kidnapped by traffickers. Many end up in anonymous mass graves. The violence has stopped many Central Americans and Mexicans from attempting to make the journey, a major factor in the decline in illegal immigration to the United States.