At least 10 people were killed in a Brazilian prison uprising late on Saturday, local media said, adding to chaos in the country's penitentiary system in which more than 116 inmates have died in gang warfare since the start of the year.
The latest outburst of violence took place at the Alcaçuz jail in the northeastern state of Rio Grande do Norte, Folha de S. Paulo newspaper said, citing the state's press secretariat.
The state government's press office was not immediately available to confirm the reports.
Police have not yet entered the Alcaçuz jail and the death toll could rise further, Folha and other newspapers said.
Behind the bloodletting is an escalating feud between some of Brazil's most powerful drug gangs, who ended two decades of an uneasy working relationship about six months ago.
This month's killings in Brazil's deadliest jail uprising in decades has exposed escalating turf wars between São Paulo-based gang Primeiro Comando da Capital, or PCC, and the Rio de Janeiro-based Comando Vermelho that risk plunging a chaotic penitentiary system deeper into violence.
It was not immediately clear what drug faction was behind Saturday's killings.