Police in Mexico say 13 people were killed Saturday in and around the Pacific coast resort city of Acapulco.
Officials said five of the dead were police officers whose patrol was attacked in the outskirts of town.
The bodies of eight civilians were discovered in different parts of Acapulco. Four of those victims had been decapitated.
Police say they suspect drug traffickers were involved in the killings.
More than 14,000 people have been killed in drug-related violence in Mexico in recent years, despite the deployment of nearly 50,000 troops to fight Mexican drug cartels.
President Felipe Calderon ordered the security forces to fight drug violence and trafficking after his election in 2006.
Mexico's northern border areas have been particularly violent as drug cartels battle each other for control of trafficking routes into the United States.
Some information for this report provided by AFP and Reuters.