Prolonged gun battles between police and drug traffickers left at least 14 people dead yesterday in Rio, including a 14-year-old girl who was reportedly shot through the chest while she surfed the internet.

The deaths came during a series of major police assaults on the city's slums, including one favela that serves as the HQ of the city's largest drug gang.

Triggered by a spate of attacks on police and drivers, the incursions began on Tuesday and involved hundreds of heavily armed police operatives, bulletproof vehicles and helicopters.

About 150 people were arrested during the sweeps by 17,500 officers while at least 22 people have been killed since Sunday, according to Rio's military police. The wounded have included two policemen and an 81-year-old man while an estimated 17,000 children were left unable to attend lessons as a result of the clashes.

"We did not start this war," Colonel Lima Castro, a spokesman for Rio's military police said last night. "We were provoked and we will emerge victorious."

The massive operations in at least 20 Rio favelas followed a wave of apparently co-ordinated attacks by drug traffickers who torched buses and cars and planted homemade bombs in various locations.

The attacks were reportedly instigated by Rio's oldest and most powerful drug faction, the Red Command, as a reaction against official attempts to pacify the favelas which have so far seen several suspected gangsters expelled.

After Tuesday's operations, the confrontations erupted again yesterday when armed police poured into the Complexo da Penha, a sprawling labyrinth of slums which is home to leading members of the Red Command faction.

It is controlled by scores of fresh-faced gang members armed with assault rifles and machine guns.

Helicopter images shot by one TV channel showed dozens of gang members, brandishing handguns and assault rifles, gathered at an entrance to the community.

Last night gunfights continued, cars burned and police roadblocks were set up across the city. Internet rumours of impending attacks, in shopping malls and in the city's beachside south zone, spread rapidly.

"[The rumours] only help the traffickers," Brazil's security secretary, José Mariano Beltrame, told Rio's nightly news. "We have to anticipate these actions."

Rio's governor, Sérgio Cabral, also took to the airwaves. "This is an act of despair," he said. "We will carry on with the same policy of retaking territory."

One civil police officer told the Guardian that authorities expected further attacks. "There's going to be trouble," he said.