Riot police use pepper spray as they clash with protesters, as tens of thousands of protesters block the main street to the financial Central district outside the government headquarters in Hong Kong September 28, 2014. The leader of a Hong Kong movement seeking greater democracy announced in the early hours of Sunday the launch of a campaign to blockade the heart of the financial centre to demand greater freedoms in the former British colony. REUTERS/Bobby Yip (CHINA - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)

Riot police use tear gas and water canon to disperse protesters as they try to march to the parliament during a protest against Turkey's ruling Ak Party (AKP) and Prime Minister Tayyip Erdogan in Ankara February 13, 2014. REUTERS/Umit Bektas (TURKEY - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)

A Turkish riot policeman uses tear gas as people protest against the destruction of trees in a park brought about by a pedestrian project, in Taksim Square in central Istanbul May 28, 2013. REUTERS/Osman Orsal (TURKEY - Tags: POLITICS CIVIL UNREST ENVIRONMENT TPX IMAGES OF THE DAY)

A protester holding a shield attempts to block a jet of water from a police water cannon during clashes in Istanbul's Taksim Square June 11, 2013. Riot police fired tear gas and water cannon at hundreds of protesters armed with rocks and fireworks on Tuesday as they tried to take back control of a central Istanbul square at the heart of fierce anti-government demonstrations. REUTERS/Osman Orsal (TURKEY - Tags: CIVIL UNREST POLITICS)

A former member of the Salvadoran army is hit by pepper spray as he tries to climb over a barricade during a protest outside a hotel where local congress members were meeting in San Salvador June 27, 2013. Hundreds of veterans marched in the capital to demand the passage of a law that will see the payment of compensation, monthly pensions and other benefits for veterans, according to local media. REUTERS/Ulises Rodriguez (EL SALVADOR - Tags: POLITICS CIVIL UNREST MILITARY)

A police officer fires pepper spray at a protester wearing a Guy Fawkes mask on the back of his head to stop a demonstration in Salvador June 20, 2013. Protesters are expected to flood more than 100 Brazilian cities and surround two international football matches later on Thursday, as lower transport fares and promises of better public services fail to stem the tide of discontent in Latin America's biggest country. REUTERS/Jorge Silva (BRAZIL - Tags: SPORT SOCCER CIVIL UNREST POLITICS CRIME LAW TPX IMAGES OF THE DAY)

A Pro-Telangana and India's main opposition Bharatiya Janata Party (BJP) supporter is hit by a police water cannon as he tries to climb over a barricade during a protest in New Delhi September 4, 2012. The supporters were demanding a separate Telangana state carved out of the southern Indian state of Andhra Pradesh, supporters said. REUTERS/Adnan Abidi (INDIA - Tags: POLITICS CIVIL UNREST)

A man is hit by a jet of water as riot police use a water cannon to disperse demonstrators during a protest against Turkey's Prime Minister Tayyip Erdogan and his ruling Justice and Development Party (AKP) in central Ankara June 1, 2013. Erdogan made a defiant call for an end to the fiercest anti-government demonstrations in years on Saturday, as thousands of protesters clashed with riot police in Istanbul and Ankara for a second day. REUTERS/Umit Bektas (TURKEY - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)

A University of California Davis police officer pepper-sprays students during their sit-in at an "Occupy UCD" demonstration in Davis, California November 18, 2011. UC Davis Chancellor Linda Katehi apologized to jeering students on November 21 for police use of pepper spray against campus protesters in a standoff captured by video and widely replayed on television and the Internet. Faculty and student critics of Friday's confrontation, some of whom demanded the chancellor's resignation, said it had damaged the school's image and the climate for free expression at the university. Photo taken November 18, 2011. REUTERS/Brian Nguyen (UNITED STATES - Tags: CIVIL UNREST EDUCATION CRIME LAW TPX IMAGES OF THE DAY)

An Israeli border police officer uses pepper spray to disperse Palestinian activists after the group set up tents and makeshift structures in protest against a nearby Jewish settlement in the West Bank village of Burin, south of Nablus February 2, 2013. Palestinians who set up a makeshift encampment in the occupied West Bank on Saturday clashed with Israeli soldiers and settlers and some light injuries were sustained.
REUTERS/Mohamad Torokman (WEST BANK - Tags: POLITICS RELIGION CIVIL UNREST TPX IMAGES OF THE DAY)

A police officer uses pepper spray on supporters of a native Indian community living at the Brazilian Indian Museum during a protest against the community's eviction in Rio de Janeiro March 22, 2013. Brazilian military police took position early morning outside the abandoned museum, where the community of around 30 native Indians have been living in since 2006. The community was ordered to leave the museum in 72 hours by court officials since last week, local media reported. Most of the Indians later left the museum after making a deal with the authorities. REUTERS/Ricardo Moraes (BRAZIL - Tags: CIVIL UNREST POLITICS REAL ESTATE BUSINESS SOCIETY)

Student protesters react as police spray foam to extinguish burning tires during a demonstration against the government's plans to raise fuel price, outside the parliament in Jakarta June 17, 2013. Indonesia's parliament could pass measures on Monday paving the way for a 33 percent rise in the country's fuel prices to reduce a government subsidy bill that has cast a shadow over Southeast Asia's biggest economy. REUTERS/Beawiharta (INDONESIA - Tags: ENERGY POLITICS CIVIL UNREST BUSINESS)

Royal Canadian Mounted Police officers pepper spray demonstrators as they attack a barricade during an anti-poverty protest on Parliament Hill in Ottawa, November 17. About 300 protestors clashed with police while demonstrating for federal funding for low income housing.

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Israeli border police officers use pepper spray as they detain an injured Palestinian protester during clashes on Land Day after Friday prayers outside Damascus Gate in Jerusalem's Old City March 30, 2012. Israeli security forces fired rubber bullets, tear gas and stun grenades to break up groups of Palestinian stone-throwers on Friday as annual Land Day rallies turned violent. Police said they had made five arrests at Damascus Gate. Land Day commemorates the killing by security forces of six Arabs in 1976 during protests against government plans to confiscate land in northern Israel's Galilee region. REUTERS/Ammar Awad (JERUSALEM - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY) BEST QUALITY AVAILABLE

A policemen sprays tear gas on his comrades who are demanding better conditions during a demonstration in La Paz April 3, 2008. A police physical security battalion has been on strike against the police chief commander for two weeks. REUTERS/Gaston Brito (BOLIVIA)

Hungarian riot police uses teargas against a protestor in front of the Parliament building in Budapest February 11, 2008. Protestors gathered outside parliament to protest against the government's reform bill which will let private capital into the health insurance system. REUTERS/Karoly Arvai (HUNGARY)

German police officer uses pepper spray against a protester in Leitstade near Dannenberg, November 7,2010. German police clashed on Sunday with anti-nuclear activists trying to disrupt a shipment of Castor rail containers of reprocessed German nuclear waste to a storage dump, using truncheons and tear gas to clear a blocked rail line. REUTERS/Christian Charisius (GERMANY - Tags: POLITICS CIVIL UNREST ENVIRONMENT)

A protester reacts as riot policemen spray pepper gas during clashes outside the National Legislative Assembly in Panama City June 19, 2012. Students and labor unions from different organizations on Tuesday protested against a new law which allows the government to sell shares in government services, such as telecommunications and electricity. REUTERS/Carlos Jasso (PANAMA - Tags: BUSINESS CIVIL UNREST POLITICS EDUCATION TPX IMAGES OF THE DAY)