Shots were fired and police shouted through bullhorns for protesters to disperse, witnesses said, as chaos erupted in Ferguson, Missouri, which has been racked by protests since an unarmed black teenager was shot by police last week.
Hundreds of protesters fled to safety after authorities fired canisters of smoke to disperse them hours ahead of a planned midnight curfew.
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The announcement came a day after a famine was declared in two areas of South Sudan following three years of civil war and severe inflation.
It is unclear what their alleged plans were.
Anti-terror police are currently questioning the men who were arrested at three separate locations in France.