Clashes have broken out at a Brazilian prison where 26 prisoners were recently killed in a confrontation.
Live images on Globo television showed hundreds of inmates throwing rocks at each other and setting up barriers on Thursday inside the Alcacuz Penitentiary, outside the northeastern city of Natal.
Inmates appeared to be separating themselves into two groups with makeshift barriers of pieces of wood and other material. Injured prisoners were seen being carried off.
No prison guards could be seen.
Prison authorities did not immediately respond to emails and phone calls seeking information about the clash.
Confrontations between two gangs in the prison erupted over the weekend, resulting in the 26 deaths. Many of the dead were dismembered.
Authorities said members of the Sao Paulo-based First Command, Brazil's largest criminal gang, known by the Portuguese acronym PCC, fought with local gang Crime Syndicate of Rio Grande do Norte.
On Wednesday, a heavily armed military police force entered the prison without violence. Authorities said they transferred 220 inmates to other prisons to avoid more clashes.
Brazil is experiencing a wave of prison killings from warring gangs. At least 126 people have died since the beginning of the year.
Security experts say the trigger was the break-up of a long truce last year between the PCC and Red Command, a large gang based in Rio de Janeiro.
Previously, the two groups worked together to ensure a heavy flow of drugs and arms over Brazil's borders.
Five days later, PCC members killed 33 people at a Roraima state prison. Brutal scenes captured on a mobile phone video spread widely on social media, in which the inmates are seen hacking away at bodies in acts of revenge.