A woman descends into a tunnel nearly a mile (1.6 km) long running into California from Tecate near the Pacific coast, December 4, 2007, after it was discovered on Monday by law enforcement agencies. Gunmen killed the police chief of Tecate, a Mexican city bordering California, on Tuesday by shooting him some 50 times in an apparent revenge attack after police found the drug-smuggling tunnel under the border. REUTERS/Jorge Duenes (MEXICO)