Gruesome killings
 
It is currently embroiled in a brutal fight with the rival Gulf cartel, based south of Texas, for control of lucrative drug smuggling routes.
 
More than 2,500 people have died in often gruesome killings linked to battles between drug cartels and also with Mexican authorities.
 
The killings have continued despite Felipe Calderon, the Mexican president, launching a year long army crackdown on their activities in which scores of drug traffickers have been arrested and dozens extradited to the United States.
 
Calderon has deployed 25,000 troops and federal police to crush the cartels - including 3,000 to the town of Tijuana alone.
 
Last week the bodies of six kidnap victims were found in a house in Tijuana following a gun battle between security forces and alleged members of the Tijuana drug cartel, also known as Arellano Felix.
 
Four people were hurt in the fighting, which took place near a school in the city.