More than 50 bodies were found in mass graves Wednesday in the same area of northern Mexico where 72 migrants were massacred last year, authorities said.
Officials in the state of Tamaulipas said they found 59 bodies in eight graves during an investigation of the March 25 abduction of a busload of passengers. One of the graves had 43 corpses.
A statement from the Tamaulipas prosecutor's office said a joint state and federal investigation led to the arrests of 11 suspects and the rescue of five captives. It did not give the identities of the suspects or of those rescued.
Officials said they were seeking to identify the dead to determine whether they were among those seized from the bus.
Tamaulipas Gov. Egidio Torre Cantu "energetically condemned" the crimes and vowed to work closely with federal authorities, the statement said.
The bodies were found in San Fernando, a rural county in Tamaulipas. Dozens of U.S.-bound migrants from Central and South America were found shot to death in August on a ranch in Tamaulipas about 90 miles from the Texas border.
Mexican authorities said those migrants were killed by members of the Zetas drug trafficking gang, which is based in Tamaulipas and has branched into migrant-trafficking, extortion and kidnapping. Officials said the migrants apparently were killed after refusing to go to work for the gang, one of the most violent in Mexico.
Migrants traversing Mexico on their way to the United States are often targets of robbery and extortion attempts.
The Zetas once served as the armed wing of the Gulf cartel, but the group has been at war with its former allies for more than a year, terrifying residents across the border state and leaving scores of gunmen dead.
Numerous mass graves have been found across Mexico as drug gangs have battled each other and fought government forces sent to pursue them under President Felipe Calderon's 4-year-old crackdown on traffickers.
More than 35,000 people have died since the start of the anti-crime offensive in late 2006, mostly because of turf feuds between drug-trafficking groups.
Tamaulipas, which hugs the Texas border and the Gulf of Mexico, has become an emblem of the reign of fear gripping many parts of the country. The governor's brother, Rodolfo Torre Cantu, was assassinated last year only days before he was expected to win the gubernatorial election. Egidio Torre Cantu was chosen to take his place.