..REYNOSA, Mexico - A car explodes outside a police station, another outside a television station. A gang is suspected of massacring 72 migrants. A prosecutor investigating those deaths suddenly disappears. Mexico's drug cartels seem to be adopting the tactics of war zones half a world away. The violence appears to have contributed to fewer migrants crossing the border into the U.S., officials say, as they have to traverse some of Mexico's most dangerous territory to get to Texas. Mexican officials, meanwhile, warn that there likely will be more in the coming months. "Violence will persist and even intensify," President Felipe Calderón said at a forum on security where he vowed he would not back down. If authorities confirm the explosions were car bombs, it would mean a total of four such explosives have been used this year in Mexico - a new and frightening tactic that officials say the cartels are using in the escalating drug war. No drug gangs claimed responsibility for Friday's violence in the northern state of Tamaulipas. A survivor of the massacre, however, said the killers identified themselves as Zetas, a group of former Mexican army special-forces soldiers who are now a lethal drug gang that has taken to extorting migrants. Kidnappings and attacks on government security patrols are rampant in the highways surrounding San Fernando, where the bodies of the 72 Central and South American migrants were discovered on a ranch Tuesday, bound, blindfolded and slumped against a wall. 'Violence will intensify,' Calderón warns In other words - Mexico is doomed and the cartels will now govern.