The death of the 18-year-old Michael Brown in early August sparked several weeks of riots in the St. Louis suburb and exposed racial tensions that have been building up for years.
Demonstrators blocked several streets, shouting insults at police officers. They began throwing stones at police, setting cars on fire and breaking into the local shops.
Police used tear gas to disperse the rioters. Media reports say shots were heard in the city. US President Barack Obama called for calm in the wake of the grand jury’s announcement.
Last week, Missouri Governor Jay Nixon announced a state of emergency that would allow the deployment of the National Guard troops. The FBI sent some 100 agents to help deal with the possible unrest.