Rioters scuffle with police on a street in Mongkok district of Hong Kong, Tuesday, February 9, 2016. Rioters clashed with police overnight and into the early hours of Tuesday in a crowded area of Kowloon. The unrest started when local authorities tried to prevent street food sellers from operating on Monday night. Activists who are dissatisfied with Hong Kong's administration took part in the clashes, local media reports said. (Photo by Kin Cheung/AP Photo)

An injured supporter of Kenyan opposition leader Raila Odinga receives assistance in Nairobi, Kenya on November 17, 2017. Kenyan police have used tear gas and water cannons to disperse supporters of opposition leader Raila Odinga who are trying to gather near the country's main airport and Uhuru park to welcome him back from an overseas trip. (Photo by Baz Ratner/Reuters)

Police officers carry an opposition activist, who was detained while taking part in an unauthorized rally, at the Triumfalnaya Square in central Moscow, late on December 6, 2011.

Photo by: Sergey Muhamedov; Source: LiveJournal

Police clash with “Occupy Melbourne” protestors on October 21, 2011 in Melbourne, Australia. Protesters and riot police clashed in Melbourne today after police, acting on a Melbourne City Council eviction order, attempted to break up the crowd of hundreds that had been positioned in City Square for a week. (Photo by Mark Dadswell/Getty Images)

A woman cries after riot police dispersed demonstrators during protests to oust Narok county Governor Samuel Tunai in Narok, Kenya, January 26, 2015. At least seven people were injured on Monday in clashes between Kenyan police and protesters from the Maasai ethnic group who accuse a local governor of corrupt handling of tourism funds from the Maasai Mara game reserve, the Kenya Red Cross said. (Photo by Thomas Mukoya/Reuters)

Kurdish gunmen hold their rifles in front of the burning house of a Shi'ite militiaman during clashes in Tuz Khurmato, Iraq, April 24, 2016. (Photo by Goran Tomasevic/Reuters)

An anti-government demonstrator argues with a Bolivarian National Police officer during a march toward the headquarters of the national electoral body, CNE, in Caracas, Venezuela, Wednesday, May 18, 2016. Opposition protesters were blocked from reaching the CNE as they demand the government allow it to pursue a recall referendum against Venezuela's President Nicolas Maduro. (Photo by Fernando Llano/AP Photo)

Russian riot policemen beat young PREGNANT female anti-Putin activist during a protest rally against the Presidential inauguration of Vladimir Putin on May 6, 2012 in Moscow, Russia.