A demonstrator with his face covered jumps over a burning barricade in Cinelandia square during a march in support of teachers on strike in Rio de Janeiro, Brazil, Oct. 7, 2013.
Teachers have been on strike demanding better pay for almost two months.
A man wears a mask during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
A demonstrator with his face covered stands next to a burning barricade near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered break ATM machines inside a bank after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered take cover behind a sign that reads "Memorias Postumas, Machado de Assis" or "The Posthumous Memoirs-Machado de Assis," near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered try to invade the City Council after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
A demonstrator wears a gas mask over a batman costume during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Firefighters throw water onto a barricade set alight near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Protesters shout slogans holding banners that reads 'Teachers squad" during a march in support of teachers on strike in Rio de Janeiro, Brazil, Monday, Oct. 7, 2013. Teachers have been on strike demanding better pay for almost two months.
A demonstrator wearing a gas mask runs from tear gas fired by riot police at Cinelandia square during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Riot police officers move toward a bus set on fire by demonstrators near Cinelandia square during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
A woman protects herself from tear gas fired by police near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Brazilian policemen take position near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered try to enter the City Council during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Brazilian policemen take position near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
A demonstrator with his face covered during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered take cover from tear gas fired by riot police outside the City Council after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
People pack Cinelandia square during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Masked protesters set a bus on fire near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered take cover from tear gas fired by riot police outside the City Council during a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Demonstrators with their faces covered thow stones at riot police near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.
Riot police officers walk past a bus set on fire by masked protesters near Cinelandia square after a march in support of teachers on strike in Rio de Janeiro, Oct. 7, 2013.