You people.
Medias willl almost always blow protests out of proportion. They are just waiting for the moment someone from the protester does something wrong. From my experience in going to peaceful protest, it's almost always the cops starting it -- or, in a few cases, masked people coming to riot and using the chance to make some trouble, which has nothing to do with the protestors themselves.
This has nothing to do with being a free country. The number of times cops crack down on peaceful protests and uses too much force or just stir up trouble is a proof that it is not this much of a free country. But you'd never get this just from looking at the biased media.
I mean, it even clearly says in the article that it was after the end of a peaceful protest. The protest was fine. They were not too clear about how exactly the trouble came about, and for this, I am suspicious. But maybe that's just 'cause I know from too many first or second hand experience how these things go.