Bodies of 10 men and a woman have been discovered on the outskirts of the Mexican capital, police said.
Two wounded individuals were also found nearby. Police said they have not yet determined the motive behind the murders.
Most of the victims - discovered Friday - were shot dead in another place and later abandoned in Valle de Chalco town on the capital's outskirts, they said.
Some 40,000 people have been killed in drug-related violence in Mexico since December 2006, when President Felipe Calderon took office.