India, Feb. 23 -- Following the death of one of the world's most wanted drug lords, 'El Mencho', the United States has issued an urgent warning for Americans in parts of Mexico following a major security operation against a powerful cartel leader.

"Due to ongoing security operations and related road blockages and criminal activity, U.S. citizens in the named locations should shelter in place until further notice," said the state department in its security alert.

The US State Department advised American citizens in several Mexican states including Jalisco State (including Puerto Vallarta, Chapala, and Guadalajara), Tamaulipas State (including Reynosa and other municipalities), areas of Michoacan State, Guerrero State, and Nuevo Leon Stat...