Mexican officials say at least 40 people were killed when a prison riot erupted Sunday in the northern part of the country.
Officials said a fight broke out in the early morning hours between prisoners and guards in the Apodoca prison, just outside the city of Monterrey. The official said authorities later regained control of the prison.
Family members of the inmates have gathered outside the prison, waiting to learn details from the incident and the status of their loved ones.
Deadly fights occasionally break out in Mexican prisons, sometimes due to rivalries between powerful drug cartels.
Last month, 31 inmates died during a prison riot also in northern Mexico.
The country's northern border areas have been the worst hit by drug violence that has left tens of thousands of people dead since President Felipe Calderon launched a crackdown on the cartels, after taking office in 2006.
Some information for this report was provided by AP, AFP and Reuters.