Monterrey and the state it is situated in - Nuevo Leon - has become one of Mexico's most violent places after a turf war broke out between two major drug cartels.
More than 600 people have been killed in the last year, as a result the state and authorities have launched an unprecedented war against drug gangs.
And as Al Jazeera's Mariana Sanchez reports from Monterrey, fear and frustration have gripped the city.
