The arrested Arrest suspects have indicated Statement that the victims were Gulf Cartel members , but the Mexican authorities have not ruled out Legal_rulings the possibility that they were U.S.-bound migrants .

The authorities have blamed Judgment_communication much of the violence Violence on Los Zetas – a cartel originally set up by ex-commandos that deserted Escaping the Mexican Army in the 1990s – and the Sinaloa Cartel , an organization originally headed by Joaquín Guzmán Loera ( a.k.a .

The killers , however , confessed Reveal_secret that they abducted Kidnapping and killed Killing the passengers because they feared their rivals , the Gulf Cartel , were getting Getting reinforcements Cause_change_of_strength from other states .

In addition , the killers claimed Statement to have investigated Criminal_investigation passengers ' cellphones and text messages to determine Deciding if they were involved Participation with the Gulf Cartel or not , and that they were particularly worried about buses coming in from the states of Durango and Michoacán , two strongholds of the rival La Familia and the Sinaloa Cartels .

Relief agencies distributed Supply food and aid Assistance to the hardest hit Attack areas , although in Tamaulipas , residents had to rely on assistance Assistance from the local Gulf Cartel .

The fight Hostile_encounter was between Los Zetas and the Gulf Cartel , two drug cartels that operate Being_in_operation in northeastern Mexico .

The guards of the prison allowed Preventing_or_letting the Zeta members to surge Motion_directional from Cellblock C into Cellblock D and attack the Gulf Cartel members , who were sleeping .

It was later confirmed Check that the riot Violence and brawl Hostile_encounter `` served as cover for a massive jailbreak '' for the members of the Zetas drug cartel , who attacked Attack the Gulf Cartel inmates .

After the split of the Gulf Cartel and Los Zetas in early 2010 , both groups have been battling Hostile_encounter for Monterrey and other areas in northeastern Mexico .