At least one demonstrator was injured as several shots were fired during clashes in the US city of Ferguson late Sunday.
An AFP journalist heard about two dozen shots ring out and saw one bloodied protester lying on the ground.
The St Louis County police department tweeted that "multiple shots" had been fired, and local media reported that one person had been taken to hospital.
The violence came at the end of a day of somber remembrance to mark the anniversary of the shooting of black teen Michael Brown by a white police officer in a case that triggered violent unrest.
Demonstrations had been peaceful all day but a rowdy group of protesters later looted at least one store and faced off against police officers clad in riot gear.