MEXICO CITY – Four decapitated bodies were found on a street in the Mexican city of Culiacan, blocks away from their severed heads.

Three of the beheaded bodies were found inside black, plastic bags on Wednesday, while the fourth was wrapped in a blanket, according to the prosecutor's office in Sinaloa state, where Culiacan is located. Authorities said they believe the killings were drug gang-related.

Police found the heads inside separate white bags on a nearby street in Culiacan, a center for the powerful Sinaloa drug cartel.

“You're next Chapo. You ungrateful traitor,” read a note found on a piece of cardboard nearby.

Joaquin “Chapo” Guzman is head of the Sinaloa cartel. He escaped from a Mexican prison in 2001 and is among the most wanted drug lords in the United States and Mexico.

Four gunmen were killed hours later, after opening fire on federal police patrolling Culiacan. Under attack, police shot back at the home where the gunmen were holed up, killing the four assailants and capturing two others. Police said they seized 16 assault rifles and ammunition in the house after the confrontation.

President Felipe Calderón has deployed 25,000 soldiers across the country to wrest back territory from drug gangs, which have responded with bold attacks on the military and police. More than 4,000 people have been killed in turf wars, assassinations and shootouts since 2005.