A grand jury has decided not to charge a Missouri policeman over the death of unarmed black teenager Michael Brown.
Announcing the decision, state prosecutor Robert McCulloch said the jury exhaustively examined evidence.
Mr Brown’s family said they were “profoundly disappointed”. Police said shots were fired and cars vandalised after the announcement.
Michael Brown, 18, was killed by Darren Wilson in Ferguson on 9 August. His death sparked weeks of demonstrations.
Some protests turned violent, and police were criticised for responding with military grade riot equipment.
As the decision was announced late on Monday, hundreds of protesters gathered outside the police department in Ferguson, a suburb of St Louis.
They followed on radios and mobile phones as Mr McCulloch made a statement explaining the decision.
Tear gas
The prosecutor said that the jury’s job had been to separate fact from fiction, and that some witness statements had been contradicted by physical evidence.
Mr Brown’s family had joined public officials in calling for calm.
After the announcement, they issued a statement saying they were “profoundly disappointed that the killer of our child will not face the consequence of his actions”.
A little later, Ferguson police said on their Twitter feed that shots had been fired, and some protesters were seen vandalising cars. Police responded with tear gas.
President Barack Obama made a statement urging those who disagreed with the grand jury’s decision to protest peacefully.
The case has stoked racial tensions in the US, with many in the African American community calling for Mr Wilson to be charged with murder.
Protesters have been chanting, “Hands up, don’t shoot” – a reference to statements by some witnesses who said Mr Brown had his hands up in apparent surrender to the officer when he was shot.
Police have said there was a struggle between the teenager and the officer before the shooting.
Missouri Governor Jay Nixon had declared a state of emergency in the area and called in 400 National Guard troops in anticipation of protests ahead of Monday’s announcement.
Source: BBC