Police clash with masked demonstrators in Athens on October 20, 2011. Clashes have broken out in central Athens between rival groups of demonstrators, amid a second day of mass demonstrations against a new round of austerity measures being debated in parliament. Police fired tear gas and stun grenades outside parliament as several hundred masked youths attacked peaceful demonstrators from a Communist-backed trade union who had tried to isolate them from the rally. AFP PHOTO / LOUISA GOULIAMAKI