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.
Officers standing guard outside the police station in Ferguson, the St Louis suburb where Michael Brown was killed in August, were an early target.
Gunfire has also been heard and there've been reports of looting.
Police fired tear gas as the violence erupted despite appeals for calm by President Barack Obama and the state governor.
Brown's family also urged a non-violent response to the grand jury's finding.
Authorities had called in the National Guard days before the announcement to back up the police.
The scenes were an echo of the sometimes violent protests that followed the shooting.