A video showing Cleveland police shooting dead a black youth raised new questions about US police treatment of young African Americans, as calm returned to the flashpoint town of Ferguson on the Thanksgiving holiday.
Ferguson, a suburb of St Louis, had seen sometimes violent protests since Monday's explosive decision by a Missouri grand jury not to charge a white policeman who shot dead an unarmed black teen in August.
The decision revived long-standing questions about how police, especially white officers, interact with African Americans -- questions asked again after the weekend shooting in Cleveland of 12-year-old Tamir Rice.
Surveillance video released Wednesday in the Ohio City showed Rice, who was carrying a replica gun, was killed within seconds of the patrol car arriving on the scene in a park.
The officer who fired the fatal shot was new to the force, and is white.
Cleveland police also released audio from a 911 emergency call from a man who first saw the boy waving the gun, saying he thought it was "probably fake."
However, the dispatcher did not tell the officers that the gun was possibly a toy nor that the suspect was likely a youth, the tape showed.
The Cleveland branch of the National Association for the Advancement of Colored People (NAACP) said the incident "brings into question the adequacy of the selection, training and preparation of police officers."
"Police officers should be prepared to confront and address people of all races and cultures and use deadly force only as a last resort," it said.
In Ferguson, just a few dozen protesters and clergy braved rain and light snow late Wednesday to protest outside the police department in the St Louis suburb, where 18-year-old Michael Brown was killed on August 9.
"This is what democracy looks like," shouted the mainly young demonstrators, bundled up against the cold.
One or two taunted and swore at the 50 National Guard troops in riot gear who stood on duty at the police department.
Witnesses said police took one person into custody.
Protesters later marched from the police department past city hall, briefly blocking traffic. They later dispersed peacefully.
The shooting death of Brown sparked weeks of protest and a debate about race relations and heavy-handed police tactics.
The decision not to indict Officer Darren Wilson, who fired the fatal shots, has sparked fresh protests across the United States as well as a rally across the Atlantic in London.
Volunteer clean-up crews have swept the streets of Ferguson since angry crowds on Monday torched businesses and looted stores.
"I hope we can pull together as a community," Karen Gold, who owns a shop selling repurposed furniture near the Ferguson city hall, told AFP. "I want to move on from this."
Heavy security -- police, state troopers and National Guard troops -- has still been visible in the streets, but the situation appears to be stabilizing.
In Britain, thousands of sympathizers angered by Brown's treatment marched in London, chanting: "Hands up, don't shoot."
US civil rights leaders have called for more protests across the country.
A call for boycotting black Friday, the day known as the beginning of Christmas shopping season, has been announced in solidarity with Ferguson. This call is referred to as "BlackoutBlackFriday," and has gaining momentum on social media sites.