A family of seven, including three young children, were found murdered with their throats slit in a ranch outside the Gulf port city of Veracruz, a local official said on Sunday.
The bodies were discovered after neighbors noted an awful smell coming from the home outside the town of Manlio Fabio Altamirano, the Veracruz state attorney general's office said in a statement.
The state of decomposition suggested they had been murdered at least 72 hours before they were found.
Three children aged 9, 7 and 3 were among the victims, said a government official who requested anonymity.
It was the second time in less than a week that a family was attacked by suspected organized crime gangs. On August 8, gunmen killed a family of five in the Pacific coastal resort of Acapulco.
More than 55,000 gangland murders and execution-style hits have occurred since Calderon took power in December 2006 and declared a national crackdown on drug gangs. Veracruz has experienced increasing violence over the last year.
There has been a rash of deaths and violence since last week in central Mexico, a battleground between rival gangs for control over lucrative smuggling routes to the United States.
A mayor elected in Mexico's July 1 vote and his campaign manager were found shot to death in a truck Sunday morning in the state of San Luis Potosi, which lies to the northwest of Veracruz.
Those murders followed the discovery of 14 corpses early Thursday in a van on a major highway outside the state capital, also called San Luis Potosi, and 12 more bodies found in neighboring Zacatecas state on Friday.
Further to the south, federal troops killed five alleged drug gang members in the western central state of Michoacan on Friday, according to a federal police statement.
The battle took place in Holanda, a stronghold of the cult-like Knights Templar gang and near where federal forces killed the alleged drug lord Nazario Moreno, who is now venerated by local smugglers, in December 2010.
Following the raid, alleged gang members hijacked and burnt about two dozen vehicles, including buses and a truck carrying new cars, to obstruct roads in the nearby township of Apatzingan. Four federal police wounded in the battle later died, local media said.
(Reporting by Michael O'Boyle; Editing by Stacey Joyce)