It's not normal but it happens. Radical nationalism is on the rise in Europe these days. Two days ago, Jobbik members nearly lynched representative of hungarian minority in Vojvodina (Serbia) in Budapest during the day, calling him a traitor. Just like Kosovo, Vojvodina is another autonomous part of Serbia. Recently, due to poor state whole country is in, certain people started to raise a question of independence. That has been put on hold for now. But extremists probably saw a chance that Vojvodina could split from Serbia and join Hungary in the future and they blame guy they attacked for not pushing that harder.
Sadly, when government becomes weak is the time for extremists and various paramilitary groups to flourish. That is why changing the government by violent means rarely yields good results for the country.