Authorities say 27 inmates escaped from a Brazilian penitentiary crawling through the sewage system.
An official at Rio de Janeiro state's Bangu prison complex told media that 31 prisoners attempted the break on Sunday. Within hours four were recaptured still inside the sewage system.
It is unclear what the prisoners were serving time for.
Rio state's Prison Affairs Department has ordered an investigation into the prison break.
The department did not respond to repeated requests for more details.