Police in the northern state of Mexico's Tamaulipas have discovered the bodies of 14 men placed in plastic bags and left in a small delivery truck in the center of Nuevo Laredo, the state's Prosecutor General's Office said on Wednesday.

The delivery truck was left near a municipal building in Nuevo Laredo, located just across the Rio Grande from the U.S. city of Laredo, Texas.

Police suspect all of the men, aged between 30 and 35 years, were the victims of an ongoing war between drug cartels. Police also said a note was left with the bodies, which is considered the "signature" of Mexican organized crime groups. Police did not release the contents of the note.

People on Mexico's social networks have began harshly criticizing authorities for the bloody drug cartel wars, which have left at least 47,500 dead in the past six years. Mexico is gearing up for presidential elections in July and social networkers have said both the ruling party and opposition are too busy with their presidential campaign debates instead of tackling the horrendous crimes in Mexican cities.

Mexican President Felipe Calderon has deployed military troops in several of the country's states to battle organized crime and the drug cartels.

In 2011, the number of murders in Mexico topped 12,180, which is more than five percent higher than in 2010 (11, 580 murders). Murder rates are the highest in Mexico's northern states where most of the drug trafficking routes into the United States are located.