Six severed heads have been found on a road in central Mexico, in an area not normally associated with cartel violence. Local authorities made the discovery early on Tuesday morning on a route that links the broadly peaceful states of Puebla and Tlaxcala.

The heads, all belonged to males, the Tlaxcala State Attorney General's Office announced as police hunt their killer.

Messages are often left on victims' bodies by cartels seeking to threaten their rivals or punish behavior they claim violates their rules.