Tensions in Ferguson, Missouri, where the police killing of an unarmed African-American teenager last August sparked months of protests and attracted worldwide attention, have again resurfaced. Two police officers were shot early Thursday morning, following an anti-racist demonstration at a police station, although contradictory accounts have been offered as to where the shots came from. Several hours earlier the local police chief tendered his resignation, following charges of racial discrimination on the part of the force. Alexandra Hall reports from Washington. teleSUR