Rio De Janeiro, Brazil ? Gangs torched buses and attacked banks and police stations across South America’s biggest city Thursday, deepening crime fears as a wave of rampant violence entered its third day.

At least six people have been killed in nearly 100 attacks on police and civilian targets since Tuesday night in what authorities believe is retaliation for a possible transfer of gang leaders to Brazil’s first federal penitentiary.

Sao Paulo residents had trouble getting to work Thursday morning after several public transportation companies refused to dispatch buses out of fear of new attacks.

The violence comes two months after imprisoned leaders of the gang First Capital Command – known by its Portuguese initials PCC – ordered attacks against police across the city and Sao Paulo state, causing the deaths of nearly 200 police, prison guards, suspected criminals and jail inmates in one week.