RIO DE JANEIRO (Xinhua) -- Another wave of criminal attacks against police, public buildings, buses and banks were launched by suspected gang members on Monday in Sao Paulo state, the most prosperous and populous in Brazil.

The state's Public Security Secretariat registered 27 attacks during the day.

Police killed two suspects believed to be part of a gang led by jailed leaders and arrested 12 others.

In one of the most violent attacks, a homemade bomb exploded at the entrance of the state Public Prosecutors' Office, partially destroying the building and smashing windows of neighboring buildings.

Twenty-seven public buses were reportedly burned, of which 15 in the city of Sao Paulo.

Over the past three months, this was the third outbreak of violence allegedly staged by members of the First Capital Command (PCC), which is struggling to control Sao Paulo's inmate centers.

Between May 12 and May 19, the PCC launched unprecedented attacks on Sao Paulo's streets and inside dozens of prisons, leaving some 130 people dead throughout the state.

Another 100 attacks between July 11 and July 15 killed at least six people.

The gang's leader Marcos Willians Herbas Camacho was cross-examined in court last week. He was charged with ordering the first attack in May.