A raid on a Mexican prison has left nine people dead. Authorities have not yet determined the motive behind the attack, which comes amid increased violence in the country's penitentiary system.
Six unidentified gunmen staged a raid on a prison in southwestern Mexico on Friday after posing as prison guards, according to authorities. Nine people died in the subsequent shootout.
"Once in the prison, the armed group started a confrontation against inmates and later against guards in a security tower," the state prosecutor's office said in a statement.
Four inmates and five assailants were killed in the attack, One prison guard and the sixth gunman were hospitalized with gunshot wounds.
The assault occurred near the city of Iguala in Guerrero state, which has one of Mexico's highest rates of violence.
The motive behind the attack remained unclear, according to authorities.
"We currently do not know if they were planning a mass escape or if this was simply a rivalry between two criminal groups," a security official speaking on condition of anonymity told Reuters news agency.
Violence in the Mexican penitentiary system has been on the rise, according to the country's National Human Rights Commission. In November, it reported that convicts controlled roughly 60 percent of prisons across the country, news agency AFP reported.
kms/ccp (AFP, Reuters, dpa)