Civil unrest over the weekend shooting of a teenager by police continued early Monday across Greece as hooded youths clashed with riot police for a second straight day. Two days of rioting left Athens and the northern port city of Thessaloniki resembling war zones as self-styled anarchists torched cars, banks, police precincts, car dealerships, government buildings, private homes and stores and erected blazing barricades, DPA reported. Despite charges of manslaughter filed against two of the police officers allegedly involved in the shooting, the violence continued unabated. Entire streets and avenues remained blocked by burned and overturned vehicles, and garbage bins and tear gas filled the air throughout Athens and Thessaloniki. Hundreds of students taking part in the riots have sought shelter in the Polytechnic and Economic Universities, which is off limits to police under Greek law, reports said. The Polytechnic university was the scene of a major student uprising during the military dictatorship that ruled Greece from 1967-74. Early Monday, some 150 hooded youths who had sought shelter inside the Polytechnic University were reportedly still battling riot police outside the school gates, throwing stones and fire bombs. Riot police, apparently having run out of tear gas following two days of protests, were retaliating by throwing stones at the youths. Television reports said that a bookstore near the university was set ablaze in early Monday, and firefighters rushed to the scene to extinguish the flames. Prime Minister Costas Karamanlis promised a full investigation into events leading to the teenager's death. With violence in full force across Greece, he called an emergency meeting of interior and public order ministers late Sunday in an effort to find a solution. The rioting and protests began late Saturday in Athens, shortly after the shooting in the central district of Exarchia.