At least four people were hospitalised, including one person with critical injuries. Two others were treated at the scene and released. No law enforcement officers were injured.
The move came amid a crackdown against a violent Islamist group on Thursday following three days of violent protest by it to force the government to expel the French ambassador over a blasphemous caricature published in France last year.
The choice of a winning photo portraying the global pandemic was almost inevitable for the contest covering a year in which news around the globe was dominated by the virus that has killed nearly 3 million people, including more than 360,000 in hard-hit Brazil.