(AP) - Demonstrators temporarily shut down two large malls in suburban St. Louis on one of the busiest shopping days of the year Friday, as rallies were held nationwide to protest a grand jury's recent decision not to indict the police officer who fatally shot 18-year-old Michael Brown in nearby Ferguson. 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 in Richmond Heights a few miles south of Ferguson, where officer Darren Wilson fatally shot Brown, who was unarmed, in August. 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 West County Mall in nearby Des Peres. It didn't appear that any arrests were made. The protests were among the largest in the country on Black Friday, along with rallies elsewhere in the country including Chicago, New York, Seattle and northern California, where protesters chained themselves to trains. "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 Manchester, another St. Louis suburb. Monday night's announcement that Wilson, who is white, wouldn't be indicted for fatally shooting Brown, who was black, prompted violent protests 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. Mindy Elledge, who runs a watch kiosk at the Galleria, said it was working. "I think people are afraid to come here," Elledge said. With the protests going on, you never know when or where they're going to happen. 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. Malcolm London, a leader in the Black Youth Project 100, which has been organizing Chicago protests, said the group was also trying to rally support for other issues, such as more transparency from Chicago police. We are not indicting a man. We are indicting a system," London told the crowd. 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.