This is an explanation of those photos from Brazil:
At least 33 inmates have been killed after prisoners allegedly linked to Brazil's largest drug gang escaped their cells and began slaughtering fellow convicts.
The riot at the Monte Cristo Agricultural Penitentiary in Boa Vista, Roraima, which broke out at dawn, was reportedly a reaction to the prison uprising and death of around 60 people in the Amazon jungle's Manaus prison on Sunday night.
The government has been quick to blame the Roraima riot, according to daily newspaper Folha de S.Paulo, on northern rebel group the FDN (Familia do Norte).
However, a local secretary of justice, Uziel Castro, told the BBC the more prominent Primeiro Comando da Capital (PCC) was behind the killings.
A group of prisoners, now back in their cells, reportedly escaped at 2.30am before attacking inmates in what at least appears to be part of an ongoing feud between supporters of opposing militant factions.
“It’s the PCC,” said one agent, quoted by Brazilian news website Jornal O Globo, who was naming the same criminal organisation that was blamed for the Manaus violence.
There were 1,500 prisoners at the scene and 15 prison officers on duty at the time, and some of the victims were decapitated, according to reports.
“It was not worse because we were able to react,” added the officer.
The chaos was reportedly quelled after the Special Operations Battalion and military police intervened.
The prison massacre, confirmed by the region's Secretariat of Justice and Citizenship, is reportedly now the country’s third most deadly since the 1992 Carandiru executions when 111 prisoners died.
Government said the PCC, which has also been blamed for the Manaus massacre, earned $32m (£26m) in drug sales in 2012 and that almost half its 13,000 members were jailed in Sao Paulo state.
