Inmates who started a riot Sunday at the overcrowded Milton Dias Moreira prison in Rio de Janeiro took prison guards hostage, Reuters reports, citing an email from the Rio state penitentiary administration.

What's happening: Per Reuters, the email did not say how many guards are being held hostage or provide information on any deaths or injuries. This comes in the wake of a series of prison riots in the country amid a standoff between rival drug gangs. Reuters said the prison, built to hold fewer than 900 inmates, has more than 2,000.