At least 42 inmates have been found dead at four prisons in the capital of Brazil's northern Amazonas state on Monday.
Authorities said the victims appeared to have been killed by "asphyxiation" and were discovered during routine inspections at the prison facilities.
Additional reinforcements have been dispatched to boost security, they added, without providing more details.
This comes a day after 15 prisoners were killed in gang clashes in the same city.
King Charles to resume public duties after cancer diagnosis
Britain's King Charles will return to public duties next week for the first time since being diagnosed with cancer as he makes good progress following treatment and a period of recuperation, Buckingham Palace said on Friday.
India's top court declines to order any change to vote-counting process
India's Supreme Court has declined to order any change to the vote-counting process, rejecting petitions seeking a return to the ballot system or to tally all paper slips generated as proof of voting for votes recorded by electronic machines.
Fire at Brazil guesthouse leaves at least 10 dead
At least 10 people died and 11 were injured in the early hours of Friday morning in a major fire at a guesthouse in Brazil's southern city of Porto Alegre.
Gaza baby saved from dead mother's womb dies
A baby, who was delivered from her dying mother's womb in a Gaza hospital following an Israeli airstrike, has died after just a few days of life, the doctor who was caring for her said on Friday.
India begins voting in second phase of giant election
India began voting on Friday in the second phase of the world's biggest election, as Prime Minister Narendra Modi seeks a record-equalling third straight term.
BRED Abu Dhabi, Presented by Hypebeast, is back April 24-28 in Yas Bay. The line up is next level and locked in.
Get the latest UAE and world news from our award winning team of journalists. The ARN News Centre is the country's most trusted source of information.
Hear Maz & James chatting to the featured artists every month with Flash Entertainment.
The super-star and multi-award-winning singer-songwriter, Jason Derulo is bringing the heat to Dubai.
