An inmate displays a makeshift knife moments after police left the prison in the Alcacuz prison in Nisia Floresta, near Natal, Brazil, Jan. 24, 2017.

Brazil has been hit by a wave of deadly gang clashes in prisons in the north and northeast regions since the start of the year. At least 140 inmates have been killed in the violence, many decapitated or mutilated.

The clashes are the result of a split between Brazil's most powerful drug gang, the First Capital Command, or PCC, and the second-most powerful gang, the Rio de Janeiro-based Red Command.