. >> a mass grave containing at least 18 bodies has been discovered in northeastern mexico. security forces say a tipoff lead into the site. in the northern state at the center of battles. >> a grim discovery in a remote part of northeastern mexico. a massive hole in the ground that is 20 meters deep. investigators say an enormous -- an anonymous tip of lead in to it. they are not sure how many bodies they will find. >> yellow flags are used to mark the flags of remained already uncovered. heavy machinery will be used to dig out the rest of the area. >> bloody battles between rival drug gangs are common. police say the drug traffickers use this remote spot to torture and execute their victims. then they threw them into the ditch and set them alight. ms. kanter of car terrace to mexican drug cartels have led a chill of bodies nationwide. -- mexican drug cartels have led a trail of bodies nationwide. he praised the army for its help. >> there is no force more than the state force. it is not a superior in numbers and discipline but also in intelligence and knowledge. >> 25,000