Violence broke out in Brazil's largest city when masked attackers infiltrated an anti-World Cup protest.
Demonstrators burned tires, rubbish and torched at least one car while banks and other buildings in Sao Paulo were vandalized Saturday, Xinhua cited Brazilian news web site Veja as saying.
Media reports said police made 128 arrests.
It was one of a series of protests against football's signature event planned by activist group Anonymous and follows nationwide rallies during the Confederations Cup in June last year.
Marchers carried signs saying "FIFA go home" and "Wake up Brazil", a reference to the huge cost of staging the event.
Many Brazilians are concerned that while billions of dollars were being spent on stadiums, essential public services like education, health and transport remained in a precarious state.
Rallies were also held Saturday in Rio de Janeiro, Goiania and Brasilia.
The Sao Paulo violence comes amid renewed unrest in Brazil's largest cities.
In recent weeks, authorities have stepped up security in shopping malls across Rio de Janeiro and Sao Paulo following a series of flash mobs, known locally as "rolezinhos".
