Soldiers patrol a road on the outskirts of the border city of Rio Bravo in the northeastern state of Tamaulipas, Mexico January 10, 2008. Federal troops have increased their presence after two federal policemen were gunned down on Tuesday in a shootout with suspected drug gang hitmen in the border city of Reynosa. In 2007, more than 2,500 people were killed nationwide in drug-related murders despite the military clampdown on traffickers. REUTERS/Tomas Bravo (MEXICO)