US President Barack Obama issued an appeal on Monday for restraint by protesters and police after a Missouri grand jury decided not to indict a white police officer in the shooting death of a black teen last August.
In a late-night appearance in the White House briefing room, Obama also urged Americans to understand that much work remained to be done to improve relations between black Americans and law enforcement, Reuters reported.
"We need to accept that this decision was the grand jury's to make. There are Americans who agree with it and there are Americans who are deeply disappointed, even angry. It's an understandable reaction," Obama said.
Obama said there were still many parts of the country where a deep distrust existed between law enforcement and communities of color, and that steps must be taken to improve the situation, such as increasing the number of minority people who enter the police ranks.
"Some of this is the result of racial discrimination in this country and this is tragic because nobody needs good policing more than poor communities with higher crime rates," he said.
His comments came after it was decided not to charge Police officer Darren Wilson over the fatal shooting of 18-year-old Michael Brown on 9 August, which sparked the worst night of rioting yet in Ferguson, according to the BBC.
Shots were fired and cars and buildings set alight as police fired tear gas to break up the crow of protesters.
The case has stoked racial tensions in the US, where many in the African American community called for Wilson to be charged with murder.
According to the BBC there was more vandalism and looting after the ruling than on any night in August.
> Separating Fact From Fiction
The jury's decision was announced on Monday. Hundreds of protesters milled around the police department in Ferguson, following the news on radios and mobile phones.
Explaining the decision, McCulloch said the jury's job had been to separate fact from fiction, and that some witness statements had been contradicted by physical evidence.
"These grand jurors poured their hearts and soul into this process," he said.
Protesters have been chanting, "Hands up, don't shoot" - a reference to statements by some witnesses who said Brown had had his hands up in apparent surrender to the officer when he was shot.
Police say there was a struggle between the teenager and the officer before the shooting.
In his own testimony, Wilson says that before the shooting Brown pushed him back into his car, hit him and briefly grabbed his drawn gun.
The jury was made up of 12 randomly picked citizens - nine white and three black.
At least nine votes were needed in order to issue an indictment.
> Profound Disappointment
After the announcement, Brown's family issued a statement saying they were "profoundly disappointed that the killer of our child will not face the consequence of his actions".
Outside the police department, Brown's mother burst into tears.
Some in the crowd began throwing objects at a police line.
Shortly afterwards shots were fired, and protesters were seen vandalizing police cars, at least one of which was set on fire. Police responded with smoke and tear gas.
Firefighters tackled a large blaze and heavy black smoke at a retail building, with reports of a pharmacy and a pizza shop also on fire.
Several other buildings were broken into and looted.
The Federal Aviation Authority said it was restricting the path of some flights into St Louis amid the unrest.
Thousands of people also protested in other US cities including Los Angeles, Philadelphia and New York. Protesters in Oakland, California, blocked traffic on a major motorway.
