The confrontation began when about 800 law enforcement officers tried to unblock a major busy for a week by teachers, students and other supporters in Asuncion Nochixtal in the State of Oaxaca. It was then that a group of men opened fire on authorities and civilians. Data point to the fact that the police had used firearms. After a retraction, the federal police said that an armed unit was assigned to the spot after unidentified persons have "fired on the police and the population." Among the injured, some shot, are 55 police officers and 53 civilians At least 21 people were detained.