The heads were lined up on a street outside a slaughterhouse in Teloloapan, about 155 miles south of Mexico City.
The bodies have not been found, according to the Guerrero state attorney general's office.
Seven of the heads belonged to men and three to women, all aged between 20 and 35 years.
A statement from the Teloloapan police said the heads were left with a message that appeared to threaten the La Familia cartel.
The warning said: 'This is going to happen to all those who support the FM.'
La Familia is based in Michoacan state, which lies to the east of Guerrero. Both states have suffered in recent years from fighting among drug gangs. Authorities say La Familia has been severely battered in the fighting. Read More