Deadly prison riot erupts in Mexico's Tamaulipas state
A prison riot in Mexico has left at least four people dead and six others wounded in the state capital of Tamaulipas, Ciudad Victoria.
Officials said those killed were two Tamaulipas state police officers, one security guard and one inmate.
The riot broke out when state police officers were sent into the jail to check if weapons had been smuggled in.
Witnesses described heavy gunfire from inside the jail as the security forces moved in.
Residents were asked to avoid the area but concerned relatives of the inmates gathered outside the prison compound awaiting news from those inside.
Tamaulipas security spokesman Luis Alberto Rodríguez said the authorities had responded to a "rise in tension" between rival gang members in the jail.
In March, 29 inmates escaped from the prison through a 40m-long (130ft) tunnel they had dug.
The prison is more than 40 years old and officials said it "had been neglected" in recent years and therefore lacked adequate security measures.
Prison riots are relatively common in Mexico, especially when members of rival gangs are locked up in the same facility.