Police and rioting inmates at Brazil's largest jail are involved in a tense stand-off following a wave of prison uprisings across the state of Sao Paulo. At least eight prisoners have been killed and negotiations are continuing for the release of as many as 5,000 hostages, including 1,000 children, inside the Carandiru jail in Sao Paulo, the largest in Latin America. Most jails are now back under police control, re-taken by force or negotiation since the uprising began during visiting hours on Sunday. The insurrection was most likely organised by the criminal group, First Commando of the Capital (PCC), apparently in protest at a decision to transfer its 10 top leaders from Carandiru to other prisons on Friday, following a disturbance in which five inmates were killed. The letters PCC were written in giant letters on prison courtyard walls. Eight inmates had died during the first 10 hours of riots - two of them killed by guards in Carandiru, State Security Secretary Marco Vinicio Petrelluzzi is quoted by BBC as saying. Criminal organisations are said to have special privileges within the prisons. The PCC has been reportedly responsible for a series of murders of other prisoners over recent months. There are reports of them having access to cell-phones, allowing them to continue organising criminal activities outside the jail.