MEXICO (NBC) - At least four people, including three police officers were killed during a prison shootout in northern Mexico.
Loud bursts of gunfire could be heard from the gates of the prison in Ciudad Victoria.
A police officer who emerged from the prison said inmates were armed with automatic rifles.
Police and soldiers were mobilized to try to restore order.
Relatives of prisoners said the violence broke out due to a conflict between local inmates and others who were recently transferred from a prison in Nuevo Laredo.