Police in riot gear threatened to use tear gas Wednesday as they broke up a protest at City Hall in St. Louis.
An officer at the scene shouted to demonstrators that the protest became unlawful when the demonstrators forced their way into the building. The officer threatened to use "chemical munitions" and encouraged people with children to leave the scene.
The protest was a march that included a mock trial of Darren Wilson, the police officer in the suburb of Ferguson who shot and killed unarmed teenager Michael Brown in August. A grand jury earlier this week declined to indict the officer, touching off violence in Ferguson and demonstrations across the country.