At least 21 people have been killed in a gun battle between two of Mexico's most powerful drug gangs, the Sinaloa and an offshoot known as the Beltran Layvaa.<br /><br />Police said the violent showdown took place 20km from the Mexico-US border, near the city of Nogales.<br /><br />The authorities have arrested nine people, six of whom were wounded in the clash.<br /><br />Al Jazeera's Mariana Sanchez reports. (July 03, 2010)
