Shots were fired during a march marking one year since a white police officer killed unarmed black teenager Michael Brown.
About six shots were heard as around 300 people made their way to a church on the outskirts of Ferguson, USA.
Police said is was initially unclear who fired the shots or if anyone was injured.
The march was stopped while police and ambulance crews rushed to an area behind a church where the shots were thought to have come from.
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