Unprecedented protests that began in low-income banlieue are turning ugly, with investigations under way into police brutality Before dawn on Tuesday outside the Lycée Sophie-Germain in central Paris, hundreds of teenagers dragged wheelie bins, metal barriers and shopping trolleys to build a barricade outside the front door of their secondary school. Climbing to the top of the piles of bins, pupils held banners calling for more funding and greater equality in French schools. But they were also protesting against French riot police, who have been accused by human rights groups of using…