Demonstrations turn violent in Athens - as protesters throw rocks and molotov cocktails at police outside of parliament.<br/> The presidential guard post outside the building caught fire - and a protester was set a blaze from the explosions.<br/> A group of young rioters tried to enter parliament -- reaching the front steps for the first time since the Greek crisis began - where police retaliated with tear gas.<br/> Several injuries have been reported - mainly minor burns and head wounds.<br/> The clashes come as tens of thousands took to the streets in the Greek capital - to protest new austerity measures.<br/> The 2-day strike has shut down government departments, businesses and public services.<br/> Sarah Irwin, Reuters.