The Michoacan state prosecutor’s office said the six heads – which it referred to as “cephalic extremities” – were found in Jiquilpan, a municipality near the state of Jalisco in a region that has been a battleground between competing drug gangs in recent years.
In a brief statement, it said the six men had not yet been identified and their bodies had not been found.
Meanwhile state security officials in the neighbouring state of Guerrero said gunmen entered a house and shot to death seven people in the municipality of Atoyac de Alvarez. Five were members of one family and two were a married couple.
The document from the Guerrero Coordination Group said witnesses reported that the shooting occurred around 3 a.m.
Guerrero, where Acapulco is located, is one of the states most plagued by drug gang violence.