Authorities in northern Mexico say a fight among inmates at a prison in the border city of Matamoros left at least eight prisoners injured, some of them gravely.
Tamaulipas state authorities say the injured have burns from a fire set by some of the inmates involved in Monday's brawl.
Officials say in a brief statement that state police officers and soldiers were sent in to stop the fight and put out the fire, which also damaged the prison.
Authorities didn't say if those involved in the fight are linked to drug trafficking. Tamaulipas has for years been a battleground for the Zetas and Gulf drug cartels, which have also fought each other inside prisons.