Three explosive devices detonated in Mexico's northern city Monterrey, including one near the US consulate and another by a prosecutor's office that wounded a guard, police said Saturday. The first blast went off around 9:00 pm Friday (02h00 GMT Saturday) in the Nuevo Leon state prosecutor's parking lot, 'damaging the pavement and breaking some windows, and slightly wounding a guard in the leg,' a local police official told selfnews. A second bomb exploded about two hours later in the street some 200 meters (660 feet) from the US consulate, while a third explosion was reported half an hour later outside the Topo Chico prison. The blasts damaged roads and nearby vehicles, the source said. Police have yet to identify the culprits. Monterrey, about 120 kilometers (75 miles) from the US border, is Mexico's third largest city and a home to several major companies. It has been the scene of brutal violence blamed on feuding drug cartels fighting over control of trafficking routes into the lucrative US market. Last month, the US State Department barred its personnel from taking children with them when they occupy posts at the consulate in Monterrey, citing security fears. Much of the country's drug-related violence has occurred in the northern border region, and Nuevo Leon has experienced a dramatic rise in deadly clashes between the Gulf cartel and its former allies, the Zetas. More than 28,000 people are believed to have been killed in drug cartel-related violence in Mexico since late 2006, when President Felipe Calderon launched a military crackdown. 