Police in Brazil fired tear gas and arrested scores of protesters in Sao Paulo when a march demanding free public transportation for students turned violent.
The protest on Saturday briefly blocked key streets and disrupted the transportation network in the city of 11 million, AFP reports.
A group smashed shop and bank windows and ATM machines and set a bus on fire. Subway and bus ticket machines were destroyed during the riot.
Sao Paulo's military police said a police colonel was mobbed and beaten by a group of "criminals disguised as protesters" who stole his pistol and radio.
Riot police fired tear gas to disperse the crowd and say 92 people were arrested.
Brazil is in the international spotlight as it prepares to host the World Cup next year and the Summer Olympics in 2016.
More than a million Brazilians, angry at widespread corruption and millions being spent on the sporting events rather than public services, joined protests.
