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.
US military targets IS in Syria strikes
The US military said on Saturday it carried out multiple strikes in Syria targeting ISIS as part of an operation that Washington launched in December after an attack on American personnel.
Israeli fire kills three people in Gaza, tension rises
Israeli fire killed at least three Palestinians in two separate incidents across Gaza, local health authorities said, as tension rises over continued violence.
Tens of thousands protest in Minneapolis over fatal ICE shooting
Tens of thousands of people marched through Minneapolis on Saturday to decry the fatal shooting of a woman by a US immigration agent, part of more than 1,000 rallies planned nationwide over the weekend against the federal government's deportation drive.
One dead in Australian bush fires
At least one person has died in Australia's southeast where bushfires raging for days have razed buildings, cut power to thousands of homes and burned swathes of bushland, police said on Sunday.
Trump says US needs to own Greenland to deter Russia, China
The US needs to own Greenland to prevent Russia or China from occupying it in the future, President Donald Trump said on Friday.
The legendary Craig David joins The Kris Fade Show for an unforgettable chat!
The super-star and multi-award-winning singer-songwriter, Jason Derulo is bringing the heat to Dubai.
S.N.E joins The Fusion with Eddie for an unforgettable episode! 🔥
It arrived: The UAE's First Mega Music Festival at Expo City Dubai!
