FERGUSON, Mo. -- Demonstrators temporarily shut down two large shopping malls in Missouri on the busy shopping day of Black Friday, as rallies were held nationwide to protest a grand jury's recent decision not to indict the police officer who fatally shot unarmed 18-year-old Michael Brown.

Several stores lowered their security doors or locked entrances as at least 200 protesters sprawled onto the floor while chanting, "Stop shopping and join the movement" at the Galleria mall just south of Ferguson, the St. Louis suburb where Brown was killed.

The protest prompted authorities to close the mall for about an hour Friday afternoon, while a similar protest of about 50 people had the same effect at nearby West County Mall. It didn't appear that any arrests were made.

The protest was among the largest on Friday, which also saw a large rally in Chicago and smaller ones in California and other cities.

Black Friday, the day after Thanksgiving, traditionally kicks off the holiday shopping season in the U.S. with retailers offering big discounts. Protesters were using the occasion to keep the attention focused on Brown's death, which has stoked debates nationwide about the tensions between black communities and police.

The grand jury decision, announced Monday, means that officer Darren Wilson, who is white, will not face state charges in shooting Brown's Aug. 9 death.

The decision prompted violent protests in Ferguson this week that resulted in about a dozen buildings and some cars being burned. Dozens of people were arrested.

The rallies have been ongoing but have grown more peaceful this week, as protesters turn their attention to disrupting commerce.

"We want to really let the world know that it is no longer business as usual," Chenjerai Kumanyika, an assistant professor at Clemson University in South Carolina, said at a rally at a Wal-Mart in Ferguson.

In Chicago, about 200 people gathered near the city's popular Magnificent Mile shopping district, where Kristiana Colon, 28, called Friday "a day of awareness and engagement." She's a member of the Let Us Breathe Collective, which has been taking supplies such as gas masks to protesters in Ferguson.

"We want them to think twice before spending that dollar today," she said of shoppers. "As long as black lives are put second to materialism, there will be no peace."

Other planned events around the country seemed relatively brief and thinly attended in contrast to the large demonstrations earlier this week. In Brooklyn, New York, a "Hands Up, Don't Shop" protest had been scheduled, but no one materialized.

In California, more than two dozen protesters chained themselves to trains running from Oakland to San Francisco. About 25 protesters started Friday morning by holding train doors open to protest Brown's death. No one was hurt.

- Associated Press writers Phillip Lucas and David A. Lieb in St. Louis, Mae Anderson in New York, Sara Burnett in Chicago and Kristin J. Bender in Oakland, California, contributed to this report.