Police fired smoke canisters into a crowd of about 400 demonstrators, including families with children, in Ferguson, Missouri, where they were protesting against the killing last week of an unarmed black teenager by police.
According to Reuters, police drove into the protest area in armored vehicles and shot smoke canisters at watching media representatives during a protest that had until then appeared to be peaceful.
However, the Missouri Highway Patrol said it was using the smoke canisters to disperse "aggressors" who were trying to infiltrate a law enforcement command post, and that the armored vehicles were deployed to ensure public safety.
More top news
Kitty Hawk's Flyer is an impressive attempt at tackling what humans have dreamed of for years - a flying vehicle.
Workers are to vote on industrial action as they fight to save their jobs and the future of the South Wales plant, ITV News has learned.
Lindsey Kushner said there was "no question the man is responsible, but why shouldn't you say, be aware ladies?"