Six decapitated bodies have been found dumped by the side of a road in a town in western Mexico.
Police believe the victims belong to a gang known as the Zetas, former anti-drug cartel commandos who deserted and formed a cartel of their own.
Their bodies were found in a street in Apatzingan, a stronghold of the notorious La Familia drug gang.
Earlier three people died in shootouts between Mexican soldiers and suspected drug traffickers in the port city of Tampico. Two passers-by were killed when fleeing gunmen lobbed grenades from a car as police gave chase. A suspect also died.
More than 15,000 people have been killed in drug-related violence in Mexico over the last three years.
The government has mobilised 50,000 troops to combat drug cartels engaged in turf wars over drug-running routes.