At least 52 inmates were killed in an overcrowded prison, as prisoners fought with bats, sticks and blades in Mexico Thursday. Nuevo Leon state Governor, Jaime Rodriguez said that 12 others were injured during the “pitched battle” that lasted 30 to 40 minutes at the Topo Chico prison in the northern industrial city of Monterrey.

The fight erupted following a dispute between leaders of two rival groups, including one led by a member of the Zetas drug cartel, Rodriguez said.

The 60-year-old prison houses 3,800 inmates, twice its capacity.

During the brawl, inmates set a fire in a supply room. Televsion images showed flames coming out of the prison.