RIO DE JANEIRO (Reuters) - Armored cars rolled through smoke-filled streets in Rio de Janeiro on Thursday as police battled slum-based drug gangs for a fifth consecutive day in the city slated to host the 2016 Olympics.

Live TV coverage showed heavily armed police exchanging gunfire with suspected drug traffickers in the hilly shantytowns on the city outskirts.

Police targeted the Vila Cruzeiro slum in the northern part of the city, considered a stronghold of a gang thought to be behind ordering attacks.

At least 10 armored Marine vehicles, never before used in battles in the city’s slums, or favelas, transported soldiers into Vila Cruzeiro, even as gangsters erected barriers. On television, a bus smoldered, smoke rising from a gutted shell.

“Our goal today is to take back ground from the drug traffickers. We’re taking it back and rescuing society from its position as a hostage to the drug trade,” said Colonel Alvaro Rodrigues of the military police and the head of the operation.

The violence began on Sunday as suspected gang members attacked police stations and burned vehicles. Authorities blamed the assaults on orders from imprisoned gang members angry at police efforts to take control of their turf in more than a dozen slums.

At least 30 people have been killed in this week’s violence, according to the military police. Among those was a 14-year-old girl hit on Wednesday by a bullet that strayed indoors. She died in the hospital.

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“We have no deadline to stop operations. We’re going to continue giving logistical support ... to transport police troops for as long as needed,” said Colonel Carlos Chagas, commander of the Marine logistics battalion.

Rio is among the Brazilian cities that will host the 2014 World Cup and last year was awarded the 2016 Olympics.

But the city has a history of violence and poverty that contradicts its image of shining beaches and colorful parties.

In the city of 6 million there are hundreds of poor communities, where even police are hesitant to enter. Last year gang members shot down a police helicopter, sparking raids and violence that killed 30 people.