Gangsters in the Brazilian state of Sao Paulo have stepped up their war against authorities, setting buses and banks on fire in a wave of violence that has left some 70 people dead.The unrest is apparently being directed from inside jails by a criminal gang after hundreds of its members were transferred to maximum security prisons. At least 10 banks were targeted overnight, the third night of violence. Officials are also struggling to restore order at more than 40 jails across the state. Thousands of prisoners have rioted and about 200 people have been taken hostage. The Sao Paulo district attorney, Rodrigo Pinho, said the gang leaders should already have been in a different prison as their transfer had been demanded some time ago. The president, Luiz Inacio Lua da Silva, is to call an emergency meeting to discuss the crisis but the state governor says the situation is under control. Among the dead are at least 35 police officers and prison guards.