The severed body parts of four men were stuffed into black garbage bags and dumped about 200 feet (60 meters) from a school in Sinaloa state, said state prosecutor's office spokesman Martin Gastelum. The men were ages 20 to 25, he said.

The men had been abducted Tuesday by masked assailants in the city of Navolato, Gastelum said.

The five other bodies were found near a middle school outside the northern industrial city of Monterrey, a Nuevo Leon state prosecution official said. They were in the same age range as the bodies discovered in Sinaloa and they all had been shot in the head, said the official, who agreed to confirm the incident only if he was not quoted by name

There was no sign the incidents were related and schools are currently closed for summer vacation. But youths are increasingly caught up in fighting among rival drug cartels in both Sinaloa and Nuevo Leon.

Also Saturday, the Michoacan state prosecutor's office said seven armed assailants were killed in a shootout with federal police in that western state.

A police convoy that included an armored car was patrolling the municipality of Tuxpan late Friday when it came upon a camp apparently being used by a gang, prosecutors said. It said the gunmen shot first, after a shout: "Here come the (men in) blue. Open Fire!"

The prosecutor's office said seven men clad in military uniforms and armed with AK-47s were killed during a half-hour battle with a force of police that grew to 200 officers. It said an undetermined number of gunmen escaped and no police were injured.

In the Pacific resort of Acapulco, authorities said three homes in separate neighborhoods were burned down with gasoline bombs Friday night and at least one of the targets was connected to relatives of Guerrero state's governor.

State public security secretary Ramon Almonte told The Associated Press that one of the houses previously was owned by a cousin of Gov. Angel Aguirre. Almonte would not confirm or deny news reports that a niece of the governor was the current owner of one of the other properties.

The attacks came four days after federal police captured the alleged leader of the Acapulco-based Independent Cartel, Moises Montero, nicknamed "The Korean." Montero is suspected of helping abduct and kill 20 Mexican tourists in Acapulco.

Violence has spiked recently in Acapulco. Eight men and one woman were killed in separate incidents Friday, including slayings at two restaurants and a bus station. In one case, the dismembered body of a man was found in an abandoned car.