At least 42 prisoners have been found strangled to death at three different prisons in one city in Brazil, The Guardian reports. The riots happened Monday, one day after an additional 15 died during fighting among prisoners at another Manaus prison, bringing the total dead to at least 57. Manaus is the capital of Brazil’s northern Amazonas state. In the first riot, local authorities said prisoners started fighting each other around midday Sunday and security reinforcements managed to stop the clashes within 45 minutes. Few details have been released about Monday’s killings, but Brazil’s justice and public security ministry has sent a federal task force to the city to help local officials handle the crisis. It’s not the first time this has happened: Brazil was hit by prison riots in early 2017 in which almost 100 inmates died.