Police in the St Louis suburb of Ferguson arrested 15 people after fresh protests Friday over a grand jury decision not to indict a white policeman for shooting dead an unarmed black teenager.
The arrests came after protesters forced a crowded St Louis mall to close for around two hours earlier in the day, demanding a boycott of post-Thanksgiving shopping and justice for Michael Brown.
Monday's announcement that officer Darren Wilson will not face charges sparked demonstrations, arson and eruptions of gunfire in Ferguson, and protesters were again out on the streets in the predominantly black suburb on Friday after the rallies looked to peter out.
"Police in Ferguson issued warning to protesters leave streets. Some protesters ignored warnings. Were taken into custody," St Louis County Police Department tweeted.
In a subsequent tweet, it added: "Confirmed: 15 arrested in Ferguson; one facing assault on a law enforcement officer charge. Other protesters remain peaceful."
At the nearby St Louis Galleria Mall, scores of demonstrators, including young children, had shouted "No justice, no peace," and "Stop shopping and join the movement."
About 100 people lay on the floor for four-and-a-half minutes to symbolize the more than four hours that the 18-year-old Brown lay in the road after being shot dead by Wilson in August.
Shoppers and store staff looked on bemused, while others filmed or photographed the protest, or else clapped and shouted their support.
When police officers told AFP they were clearing the building, the protesters had already left.
Although most shops reopened, others kept their doors locked and shuttered even after the mall was back in business.
Shop staff said police had ordered the closure for public safety.
"It ain't my decision," said Luke, a shoe store manager who didn't want to give his last name.
"The police thought it was in the best interest of our customers and our product to close down."
Protesters claimed success.
"It is now a movement and it is spreading across the country and around the world. Black Friday is the next step," said journalist and activist Kymone Freeman from Washington.
"Hopefully we'll see more of this. I think Black Friday protests will continue throughout the Christmas season," he added.
The grand jury decision not to indict Wilson revived long-standing questions about how police, especially white officers, interact with African Americans -- questions raised again after the weekend shooting in Cleveland of 12-year-old Tamir Rice.
Protests against the police broke out in several US cities in the aftermath of the announcement, but they appeared to have stalled with the Thanksgiving holidays shutting down much of the country this week.