Clashes erupted in Rio de Janeiro as thousands of people gathered for a march in support of striking teachers.

The march began peacefully on the Brazilian city's main avenue, but chaos broke out once night fell.

A small group of protesters threw fireworks, grenades, tear gas and smashed a gate at City Hall, where legislation was recently passed changing public teachers' pay and working hours.

Masked demonstrators also torched a bus, broke into banks, and tried to break open and set alight cashpoints.

Some protesters also pulled furniture out of banks to use as barricades as they squared off with police.

The police responded with tear gas to break up the crowds.

Protesting teachers were joined by students, civil groups, leftists and anarchist groups, some of whom are known for their violent demonstrations.

Teachers have been on strike for almost two months demanding better pay.

They said 50,000 people marched to support them before the violence broke out, but police would only confirm 10,000.

Brazil's security situation is an ongoing challenge ahead of it hosting the 2014 World Cup and 2016 Olympic Games.