Thousands of protesters demonstrated in Greece's main cities Thursday against the police killing of a teenager, while a major labor union staged work stoppages to protest the shooting and the conservative government's economic policies. In central Athens, fearful shop owners shuttered their store fronts as more than 7,000 students and other protesters marched peacefully, chanting slogans. Some demonstrators painted white crime-scene-style body outlines on the streets. Riot police kept a low-key presence, and a Christmas carousel on central Syntagma Square was full of children even as the marchers drew close. Earlier, some 1,000 demonstrators joined a Communist Party-backed peaceful march through town. The death of 15-year-old Alexandros Grigoropoulos on Dec. 6 shocked Greece and led to days of the worst rioting the country has seen in decades. Hundreds of businesses were smashed, burned or looted and gangs of youths fought running battles with riot police firing tear gas every night for a week.