Ten shot dead as police try to regain control of Brazil slums

The raids came as authorities tried to halt a wave of violence that has terrified rich and poor alike in a city that Brazil hopes to make a showpiece of the 2016 Olympics.

Officers invaded the Vila Cruzeiro favela and surrounding shantytowns early on Wednesday, sparking gunfights with gang members. One man was arrested, ten others were shot dead. Police also seized weapons including a grenade and an automatic rifle.

A spokesman said at least four buses and ten cars had been burned in Rio's poorer northern and western areas overnight - bringing the total to 22 attacks and 23 burned vehicles since Sunday.

Gangsters armed with assault rifles and grenades used cars to blockade major roads, then robbed people caught in the resulting traffic jams, setting some cars ablaze and sending black smoke billowing across the city's skyline.

Security officials say the gang attacks were intended to force authorities to stop a campaign to force gangs out of the slums - or favelas - where they have long ruled with impunity,

Thirteen such favelas have been pacified over the past two years. The plan is to free 40 - a small fraction of Rio's more than 1,000 - of gang control by the time of the football 2014 World Cup.

A programme of sending in hard-hitting squads from the elite BOPE unit to battle the gangs has been employed, who are then replaced by "Peace Officers", policemen trained to gain the trust of the favela communities.

Police said a note found on one of the burning buses on Wednesday warned that if law enforcement continues to push drug dealers out of the slums, Rio won't be able to host the Olympics. State public safety director Jose Beltrame said security forces would not be deterred.

"This is not an easy task, but it is also an opportunity to build a better city," Beltrame told Globo TV. "We are not giving back one millimetre. Their threat shows we are on the right path. They're being affected."

Rio's governor, Sergio Cabral, urged calm. "What the bandits want is panic," he told CBN radio. "We are facing a desperate reaction from criminals. But we are not going to despair."

Police have responded to the attacks by deploying riot officers on expressways into the city of six million people and sending patrols into more than 20 gang-controlled favelas to hunt down gang members they hold responsible for the attacks.

Violence has plagued Rio for decades, but most has been contained within the slums that cling to the hillsides. Now, however, at least a few of the recent attacks have spilled into middle class and wealthier neighbourhoods closer to the beach area, spreading fears that police are losing control.

"The scary part is that now it's getting close to us. Before the violence was always far away," said Olga Silveira, who was milling around a plaza in the wealthy Ipanema neighbourhood where police blew up a large, empty wooden box mistakenly feared to contain explosives.

She added: "Now we're feeling it on our flesh. The criminals have discovered the power they have and they want to show it."