Mexico City, Sep 26 (DPA) Four human heads were found Friday stashed in four coolers in the southern Mexican town of Coyuca de Catalan, where many drug gangs are active, Guerrero state authorities said.

Police also found four black bags with the remainder of the bodies, and a message whose content was not made public.

The discovery of decapitated bodies has become common in Mexico, where drug violence has claimed more than 5,000 lives in Mexico so far this year.

Also in the state of Guerrero, a mayor and his bodyguards were attacked late Thursday in an ambush in which one police officer was killed and three others were injured.

Raul Rios, the mayor of the town of Zirandaro de los Chavez, was on his way back from a meeting at state capital Chilpancingo when he was attacked by a group of people armed with AR-15 and AK-47 rifles who were on board two vehicles, the Guerrero Public Security Ministry said Friday.

Four police officers were injured in the shooting, and one of them - aged 19 - died later.