Whether Guzmán was responsible for Alfredo Beltrán's arrest is not known. However, the Beltrán Leyvas and their allies suspected he was behind it, and after Alfredo Beltrán's arrest, a formal "war" was declared. An attempt on the life of cartel head Zambada's son Vicente Zambada Niebla ("El Vincentillo") was made only hours after the declaration. Dozens of killings followed in retaliation for that attempt. The Beltrán Leyva brothers ordered the assassination of Guzmán's son, Édgar Guzmán López, on 8 May 2008, in Culiacán, which brought massive retaliation from Guzmán. They were also in conflict over the allegiance of the Flores brothers, Margarito and Pedro, leaders of a major, highly lucrative cell in Chicago responsible for distributing over two tons of cocaine every month. The Mexican military claims that Guzmán and the Beltrán Leyva brothers were at odds over Guzmán's relationship with the Valencia brothers in Michoacán.