Human rights activists and inmates' relatives accused police and riot troops Sunday of committing a massacre when they stormed Carandiru Prison to put down an uprising.
"There is no doubt that it was a massacre," said the Rev. William Sheehan, a prison chaplain who spent the weekend in the prison after the violence Friday.
"Many were shot dead for no reason at all. Some were killed by dogs. The number of dead will most likely be higher than the 111 authorities claim."
Police have denied such accusations, saying 111 prisoners were killed mainly by other inmates when a gang fight turned into a riot at the overcrowded complex.
Sao Paulo state security director Pedro Franco de Campo said more than 300 riot troops with shotguns, pistols and machine guns raided the cell block in the prison, Latin America's largest.
Flavio Augusto Saraiva Straus of the Sao Paulo Bar Association's human rights commission said police "massacred the prisoners."
Relatives returning from visits with inmates recounted stories of mass executions.