Mexican farm leader killed with 14 others on ranch

MEXICO CITY (Reuters) - Gunmen killed fifteen people on an isolated ranch in northern Mexico, including a prominent farmworker leader, in the latest grisly attack in an area overrun by drug gangs, local police said on Friday.

Margarito Montes, a well-known organizer of agricultural laborers, was among the bodies found riddled with bullets in trucks in the town of Hornos in southern Sonora, a state bordering the United States, a police spokesman said.

The cause of the crime was unknown but the killings had many of the hallmarks of hits by drug cartels, who often use automatic weapons to murder people in groups to send a message to rivals.

More than 15,000 people have been killed in drug-related violence in Mexico since President Felipe Calderon launched an army-led assault on cartels soon after taking office in 2006.

Local farmers are often caught up in drug violence, paid or coerced to grow marijuana and opium poppies for powerful traffickers, often in northern states were cartels control large swaths of territory.

(Reporting by Mica Rosenberg; editing by Mohammad Zargham)