Violence erupted very quickly after the announcement of the grand jury decision not to indict the white officer who shot dead an unarmed black teenager in Missouri.<br/> <br />Officers standing guard outside the police station in Ferguson, the St Louis suburb where Michael Brown was killed in August, were an early target.<br/> <br />Gunfire has also been heard and there've been reports of looting.<br/> <br />Police fired tear gas as the violence erupted despite appeals for calm by President Barack Obama and the state governor.<br/> <br />Brown's family also urged a non-violent response to the grand jury's finding.<br/> <br />Authorities had called in the National Guard days before the announcement to back up the police.<br/> <br />The scenes were an echo of the sometimes violent protests that followed the shooting.
