A protester is detained by police during a demonstration demanding better public services and protesting the money spent on the World Cup in Sao Paulo, Brazil, Thursday, June 12, 2014.

Masked protestors return tear gas canisters to riot police during a demonstration by people demanding better public services and against the money spent on the World Cup in Sao Paulo, Brazil on Thursday.

Police prepare to advance on one of the demonstrations.

A Brazilian riot police aims at anti-World-Cup protester.

A protester winds up to sling a stone at police after clashes erupted in Sao Paulo on Thursday.

A young woman with a gas mask is seen with protesters during a violent demonstration.

Protesters throw stones at police from behind a car.

A protestor holds a banner that reads in Portuguese; “There is not going to be World Cup!,” during a protest by people demanding better public services and against the money spent on the World Cup soccer tournament, in Sao Paulo, Brazil, Thursday, June 12, 2014.

People wearing masks protest during a demonstration demanding better public services and against the World Cup costs.

Protesters return tear gas canisters to riot police by giving them a kick.

A protestor argues with police.

A protester is detained by police during a demonstration demanding better public services and protesting the money spent on the World Cup soccer tournament in Sao Paulo, Brazil, Thursday, June 12, 2014.

A police officer stands next to a destroyed police car during a violent demonstration at the 2014 soccer World Cup in the center of Belo Horizonte , Brazil, Thursday, June 12, 2014.