Seventy-five prisoners have escaped from a jail in eastern Paraguay near the border with Brazil, officials say.
Authorities suspect many were allowed to walk free through the main gate by jail guards.
A tunnel has been discovered but officials say this could be a cover-up for the operation.
Dozens of those who escaped belong to Brazil's largest organised criminal gang, the First Command of the Capital (PCC).
The São Paulo-based group, which has almost 30,000 members, is involved in drug and arms trafficking. It operates across Brazil and in neighbouring Paraguay, Bolivia and Colombia.
After inspecting the prison complex in the eastern city of Pedro Juan Caballero on Sunday, police discovered that the entire block housing PCC members was empty. In one of the cells, they found some 200 sandbags.
One prisoner was captured as he tried to escape through the tunnel.
Interior Minister Euclides Acevedo said it was clear that prison officials were involved.
"We found the tunnel and believe that it was a cover-up to legitimise or hide the release of the prisoners. There was complicity with people" at the jail, he said in a statement.
He added that intelligence information suggested that the prisoners had been allowed to escape in smaller groups in the last few days and that this happened as the jail director was on annual leave.
Justice Minister Cecilia Pérez ordered all of the prison officials to be fired and arrested, La Nación newspaper reports (in Spanish).
Speaking to ABC Cardinal radio, she said prisoners who were on the second floor also escaped, suggesting their cells were open. She said authorities had received information that an escape was being planned and that $80,000 (£61,000) had been offered to agents, adding: "It's clear there was corruption."
It was possible that some of the escapees, who were reportedly from Brazil, had already crossed the border, Mr Acevedo added. Vehicles were found burnt-out on the Brazilian side of the border.
That border region between Brazil and Paraguay is a known drug trafficking route.