PressTV has published a news regarding to the actual situation in Brazil, caused by the FIFA World Cup. According to this, opposers to this event gathered in Sao Paulo, more specifically in the suburb of Guarulhos, to demand better life conditions. They also said that the police started throwing tear gas and stunt grenades at them, whose response was to throw ignited fireworks at the security forces over there. A video of this violent manifestation can be seen at the link of this news.
This news could not be found in any brazilian newspaper I read. No matter how much you look into it, Brazil doesn't want to make a lot of fuzz about these kind of problems regarding the World Cup. This is right now the most anticipated event for most of the people in the world, therefore is only natural that brazilian government wants to hide this kind of setbacks from their foreign customers (who are pretty much the biggest income these days).
On the other hand, brazilian government also has their hands full with the police protests, therefore this could be another reason to "justify" the fact that they didn't publish this news. Rebellious policemen are in the streets because of a lack of a fair salary and at the same time people opposing to the WC are fighting the very few "loyal" officers because of lack of decent life conditions; this doesn't precisely say a good thing about the actual government. If all of this fuzz gets to the mass media, people will stop relying on the actual government and are going to think that the country is reaching way out of their hands, therefore chaos will only become bigger and bigger and then the actual government would have to resign one way or another.
Source: http://www.presstv.ir/detail/2014/05/17/362955/sao-paolo-police-clash-with-protesters/