The clashes came less than three weeks after the city was awarded the 2016 Olympic Games. They began when a drug gang tried to invade a rival's territory and three policemen were killed when a helicopter was shot down by gunfire over the weekend.
Subsequent firefights between police and heavily armed gang members have left the affected slums in chaos. Hundreds of residents fled their homes overnight, choosing to sleep in streets away from their own neighborhoods after rumors spread that drug gangs were set to battle again.
While the violence began in a northern area near Maracana Stadium, which will host the Olympics' opening and closing ceremonies, police searching for people responsible for the downing of the helicopter launched operations in slums in Rio's south and center on Wednesday.
A police spokesman said officers killed three suspected drug traffickers during the afternoon raids, raising the death toll to 32. The official spoke on condition of anonymity, citing department rules. In the early morning, officers shot dead three other suspects in northern areas.
"We can't allow four or five criminals to cause this madness," Rio state Public Safety Director Jose Beltrame said about the drug chiefs his officers were hunting down. "Many people are suffering and feeling the pressure of this violence."
The International Olympic Committee awarded Rio the 2016 games on Oct. 2.
