In Brazil, dozens of prisoners have been killed fighting among themselves in four different jails.
The riots follow years of overcrowding, jail-break attempts and rival gangs battling for control.
Officials say some inmates were stabbed with sharpened toothbrushes while others were strangled.
Brazil has the world’s third-largest prison population.
Johannes Myburgh is a journalist in Sao Paulo, says there wouldn’t have been enough security in the prisons to break up the fights.