The bodies of four women who had been strangled and tortured were found in a field in Torreon, a city in the northern Mexican state of Coahuila, prosecutors said.

Police and soldiers taking part in "Operation Safe Laguna," which is targeting drug traffickers, found the bodies Wednesday in Metalurgica, a neighborhood in the southern section of Torreon, Coahuila Attorney General's Office spokesmen told Efe.

The victims have not been identified, but investigators estimate that they range in age from 18 to 30, a spokesman for the Laguna bureau of the AG's office said.

A tourniquet fashioned from yellow plastic rope and a piece of wood was apparently used to strangle the women, whose bodies bear signs of torture, the AG's office spokesman said.

Torreon is in the La Laguna region, which includes parts of Coahuila and neighboring Durango state.

The region is at the center of a brutal turf war between the Los Zetas and Sinaloa drug cartels.

Los Zetas controls Coahuila's largest cities, including Saltillo, the state capital, Torreon and Piedras Negras.

Cartel enforcers have carried out massacres and attacked bars and media outlets.

The government deployed Federal Police units and army troops in the region in an effort to stem the drug-related violence.

Heriberto Lazcano Lazcano, known as "El Lazca," deserted from the Mexican army in 1999 and formed Los Zetas with three other soldiers, all members of an elite special operations unit, becoming the armed wing of the Gulf drug cartel.

After several years on the payroll of the Gulf cartel, Los Zetas, considered Mexico's most violent criminal organization, went into the drug business on their own account and now control several lucrative territories.

The Sinaloa organization is the oldest drug cartel in Mexico and is led by Joaquin "El Chapo" (Shorty) Guzman, who was arrested in Guatemala in 1993 and pulled off a Hollywood-style jailbreak when he escaped from the Puente Grande maximum-security prison in the western state of Jalisco on Jan. 19, 2001.

Guzman, considered extremely violent, is one of the most-wanted criminals in Mexico and the United States, where the Drug Enforcement Administration has offered a reward of $5 million for him.

Los Zetas and the Sinaloa cartel have been fighting for control of key drug smuggling and distribution points in several parts of Mexico.

President Felipe Calderon declared war on Mexico's drug cartels shortly after taking office in December 2006, deploying tens of thousands of soldiers and Federal Police officers across the country to combat drug cartels and other criminal organizations.

More than 50,000 people, according to official figures, have died in drug-related violence since late 2006.

The Movement for Peace with Justice and Dignity, which was founded by human rights activist and poet Javier Sicilia, puts the death toll at 70,000. EFE