The violence appears to have spilled over into Germany. In Hamburg, a group calling itself Koukoulofori -- Greek for "the hood-wearers" or the "masked ones" -- claimed responsibility for an attack on a police station in the German port city on Thursday night, saying it was in revenge for the killing of the Greek teenager.
Some 10 masked people broke windows of the Hamburg police station in the bohemian Schanzenviertel district, which is known for left-wing street festivals and violent protests. They also set fire to one police car and smashed the windows of another. There have been no arrests so far.
On Thursday night unknown attackers also hurled a firebomb and bags of paint at an office of the Federal Criminal Police Office in the eastern Berlin district of Treptow.