KENYAN riot police used tear gas in central Nairobi on Friday against about 100 protesting students who threw stones at the police and at passing motorists, blocking the city’s main highway. The clashes followed similar unrest on Thursday, which broke out between supporters of rival political groups with opposing views on who should draw up a planned new constitution. Opposition MPs James Orengo and Shem Ochuodho were reportedly attacked by youths outside parliament. Students went on the rampage later Thursday after one of their number was attacked during the melee.