At least 15 people were killed in a clash that broke out at a prison in Amazonas in Brazil on Sunday, AP reported. Prison authorities said the situation at the Anisio Jobim Prison Complex in Manaus was under control.

State prison secretary Marcus Vinicius Oliveira de Ameida said the incident occurred around noon and that additional security personnel were deployed at the facility. Almeida did not specify if anyone had escaped but police helicopters were seen hovering around the city.

An investigation will be initiated into the cause of the riot, Reuters quoted Almeida as saying in a statement.

The violence follows a riot in 2017 at the same prison when 56 inmates were killed in a clash.

The country has the world’s third-largest prison population – 7,12,305 inmates till April this year, BBC reported quoting official figures.