May was a hot month in the Brazilian state of São Paulo. Four days of violence left up to 150 civilians, prison staff, police officers and suspects dead.
Over half of the state's 140 prisons were in revolt, with at least 200 hostages taken, and 80 buses and 17 bank branches burnt out. Some media sources in Brazil dubbed the events "our 9/11". Hysterical that may be, but the panic was certainly enough for the authorities to impose an unofficial curfew on São Paulo, paralysing the transport system, and shutting down schools and businesses.
News reports initially focused on the prison revolts, and attacks on police stations and vehicles. These were ordered by the state's most powerful criminal organisation, the PCC (Primeiro Comando da Capital), on 13 May, after its leaders were transferred to a new prison and denied normal privileges. But two days later it was the turn of the military police to take their revenge, inflicting a wave of summary executions on innocent victims and doubling the initial total death toll of 70.
The loudest public reaction, predictably, has been a call for tougher policing and sentencing, and a harsher prison regime. Outrage followed the news that the PCC action was directed from within the prisons using mobile phones. With a general election only months away, the hardline rhetoric is likely to intensify, as the former governor of São Paulo, Geraldo Alckmin runs for president aganst the encumbant, the Workers' Party's Lula. Lula caused anger in March when he defended the army's occupation of Rio de Janeiro's slums.
The response to the violence is ideologically charged. The crude class war rhetoric of the PCC has been a pretext for associating their activities with a whole range of supposedly "extremist", "terrorist" movements across Latin America. The real problem, according to one commentator, is that the ideas and language of the far left have "contaminated our young people".
This is really code for a kind of moral and class panic familiar in Brazil since the time of slavery. What's really being said is, "Forget the liberal nonsense about human rights and poverty - 'decent' (that is lighter skinned, middle class) Brazilians are under attack from the rabble and scum." And by "scum" they mean the young, black, working class Brazilians of the country's urban peripheries.
The current explosion of violence has deep roots in this ruling class contempt, fear and hostility for the most oppressed and deprived layers of society - something voiced in regular calls for the streets to be cleansed of the "marginals" and "vermin", meaning criminals and street children.
Brazil's obscenely overcrowded prisons and youth detention centres are a grotesque microcosm of society at large, where the state abandons and dehumanises the weak and vulnerable, while colluding with a rich and powerful minority. So for the one in five of São Paulo's prison inmates who carry the Aids virus, and the thousands of petty offenders who share hellish conditions with highly dangerous gangsters, despair and brutalisation are inevitable.
Given their neglect of the penal system, the authorities prefer to leave the effective internal management of prisons to the powerful leaders of gang factions. It seems clear that the state administration had prior knowledge of the PCC's plans, and that the rebellions and attacks were only ended through secret negotiations.
The current governor, Cláudio Lembro, has clothed the iron fist of repression in a velvet glove, hypocritically calling for the "white elite" to open its pockets and address the scourge of poverty. It is not absolute poverty that lies at the root of criminality and violence, though, but social inequality. The spectacle of conspicuous consumption by the haves cruelly raises the expectations of the have-nots, only to dash them, with potentially explosive consequences.
Brazil's class polarisation has been exacerbated by the relentless pursuit of neo-liberal policies over the last 20 years. This has left high rates of unemployment and casualisation, with 11.7 million people joining the informal sector in the 1990s.
This is the recruiting ground for both the criminal gangs and the military police, who so often act like warring brothers, colluding one moment and clashing violently the next. They offer a similar lure of power and respect for those humiliated, frustrated and marginalised by years of neglect. Disillusionment with the failed promises of the Lula administration has only made matters worse. Unless the left can offer a real alternative, the spectre of barbarism looks ever more threatening.
Dave Treece is the director of the Centre for the Study of Brazilian Culture and Society at King's College, London