Mexican officials say a drug cartel is suspected in the massacre of 72 migrants from Central and South America.
Marines found the bodies of 58 men and 14 women at a farm in northern Mexico Tuesday. Mexican authorities say the migrants are believed to have been from El Salvador, Honduras, Brazil and Ecuador.
An Ecuadorean man, claiming to be the only survivor of the massacre, said the migrants were kidnapped by an armed group and taken to the ranch, near the town of San Fernando. He told investigators the captors identified themselves as members of the Zetas drug cartel.
Officials say troops went to investigate after the Ecuadorean man approached a checkpoint and said he had been attacked at the ranch.
The troops discovered the bodies following a shootout with suspected cartel gunmen. One soldier and three of the suspects were killed.
San Fernando is about 100 kilometers south of the border with the U.S. state of Texas.
Mexico's drug cartels are locked in a violent battle for control of trafficking routes into the United States.
Mexican President Felipe Calderon launched a crackdown on the cartels in 2006. More than 28,000 people have been killed in the country's drug war since he took office.