Masked youths and looters marauded through Greek cities for a fourth night Tuesday, in an explosion of rage triggered by the police shooting of a teenager that has unleashed the most violent riots in a quarter century.
The nightly scenes of burning street barricades, looted stores and overturned cars have threatened to topple the country's increasingly unpopular conservative government, which faces mounting calls for Prime Minister Costas Karamanlis to resign.
