NEW : Violence erupts along a main commercial street . NEW : Protesters set fires , throw bottles and rocks . NEW : Police fire tear gas to disperse the crowd. Berlusconi survived by a narrow margin after the vote .
NEW : Violence erupts along a main commercial street . NEW : Protesters set fires , throw bottles and rocks . NEW : Protesters clash with police , who are using tear gas . Berlusconi survived by a narrow margin after the vote .