Protesters turned out in several U.S. cities on one of the busiest shopping days of the year Friday in response to a grand jury's decision not to indict the police officer who fatally shot 18-year-old Michael Brown in Ferguson, Missouri.

Here's a look at the protests, which are turning their attention to disrupting commerce, and the latest in the case:

NATIONWIDE RALLIES

Crowds of protesters prompted authorities to temporarily close two large shopping malls in suburban St. Louis, including the St. Louis Galleria, about 10 miles south of Ferguson, where at least 200 protesters sprawled onto the floor while chanting, "Stop shopping and join the movement."

In northern California, more than a dozen people were arrested after about 125 protesters wearing T-shirts that read "Black Lives Matter" interrupted train service from Oakland to San Francisco, with some chaining themselves to trains.

About 200 protesters gathered along Chicago's popular Magnificent Mile shopping district, at one point lying down, while about 100 people protested in New York City's Times Square with signs reading "End Racism" and "Black Lives Matter."

Dozens of people in Seattle blocked streets, and police some protesters also apparently chained doors shut at the nearby Pacific Place shopping center.

CLEANING UP

In Ferguson, community members were toting brooms and shovels Friday while helping clear an area where several businesses were damaged by the fires and looting that erupted following Monday night's grand jury announcement.

At least a dozen commercial buildings were destroyed by fires, though residents have been cleaning up and even decorating boarded-up windows with colorful artwork. There was even entertainment on Friday: Eugene Gillis was outside a burned-out building with his trumpet playing Christmas carols.

THE CASE

Brown, who was black, was unarmed when he was fatally shot by Ferguson police officer Darren Wilson, who is white, following an altercation Aug. 9 in a local street. The shooting stirred racial tensions and prompted several days of strong and at times violent protests in Ferguson, a predominantly black community patrolled by a mostly white police force.

A grand jury was later assembled, and its nine white and three black members spent three months hearing more than 70 hours of testimony from 60 witnesses. Their decision not to indict Wilson was announced Monday night.

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WHAT'S NEXT

The U.S. Justice Department has its own investigation into possible civil rights violations that could result in federal charges for Wilson, but investigators would need to satisfy a rigorous standard of proof. The federal agency also has launched a broad investigation into the Ferguson Police Department.