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.
Spanish PM Sanchez calls snap election for November 29
Spanish Prime Minister Pedro Sanchez called an early election for November 29 on Monday, in a bid to strengthen his mandate after a fragmented parliament rejected the government's key housing decrees last week amid widespread protests.
Hundreds of French schools stay closed ahead of nationwide day of student protests
Hundreds of French high schools will begin a second week of closures on Monday as protests over dilapidated schools and classrooms, overcrowding and teacher shortages precede a nationwide day of demonstrations on Tuesday.
Thousands of Imran Khan supporters start march to Pakistani capital, party says
Thousands of supporters of Pakistan's jailed former Prime Minister Imran Khan have started a long march to Islamabad to demand his release, his party said on Monday, amid deep divisions with the Pakistani leadership.
US removes bombers from UK base at centre of suspected Iranian plot
The United States has removed its B-1 bombers from a British air base one week after five men were arrested nearby on suspicion of preparing terrorist acts, a suspected plot that British Prime Minister Andy Burnham said was likely backed by Iran.
Omani court sentences two tourists for sitting on nesting turtles
A court in Oman has sentenced two tourists to a month in prison for sitting on nesting turtles at Ras Al Had reserve and posting a video on social media.
2:00pm - 6:00pm
Brent Black has the biggest stories of the day and the stuff you might have missed.
6:00pm - 7:00pm
An extra hour of the UAE's biggest radio show for your drive home.
Hate That I Made You Love Me
Ariana Grande
Sunroof
Nicky Youre
Nicole Kidman
Adéla