A woman stumbes as people run down Oxford Street, London, Britain, November 24, 2017. Police are responding to reports of an incident at London's Oxford Circus Tube station and have urged the public to avoid the area. (Photo by Peter Nicholls/Reuters)

People help a wounded person after Yishai Schlissel, an ultra-Orthodox Jew, attacked people with a knife during a gay pride parade in Jerusalem on Thursday, July 30, 2015. Schlissel lunged into a group of revelers leading Jerusalem's annual gay pride parade and stabbed several of them Thursday evening as they marched in the holy city, Israeli police and witnesses said. (Photo by Sebastian Scheiner/AP Photo)

Serbian police officers of the Special Anti-Terrorist Unit pose for a picture in their base outside Belgrade October 8, 2014. When the killing of an unarmed black teenager by a white policeman in Ferguson, Missouri, in August sparked sometimes violent protests, the response of police in camouflage gear and armoured vehicles wielding stun grenades and assault rifles seemed more like a combat operation than a public order measure. Some U.S. police departments have recently acquired U.S. military-surplus hardware from wars abroad, but there are many law enforcers around the world whose rules of engagement also allow the use of lethal force with relatively few restrictions. But for every regulation that gives police wide scope to use firearms, there is another code that sharply limits their use. In Serbia, police may use measures ranging from batons to special vehicles, water cannon and tear gas on groups of people who have gathered illegally and are behaving in a way that is violent or could cause violence, but they may use firearms only when life is endangered. (Photo by Marko Djurica/Reuters)

People lay flowers for and mourn the anti-government protesters who were killed in the past weeks’ clashes with riot police.

Russian Police detain opposition supporters during a “March of Millions” protest rally against Vladimir Putin's return in Moscow, Russia on May 6, 2012. Over 650 people were arrested including opposition leaders. (Photo by Dmitry Schedrin, Rustem Adagamov, Andrey Stenin)

A woman lies injured after an incident on Westminster Bridge in London on Wednesday, March 22, 2017. A police officer has been stabbed near to the British Parliament and the alleged assailant shot by armed police. Scotland Yard report they have been called to an incident on Westminster Bridge where several people have been injured by a car. (Photo by Toby Melville/Reuters)

Israeli police officers confront demonstrators as Israelis protest against rising housing prices and social inequalities on July 30, 2011 in Tel Aviv, Israel. Tens of thousands of Israelis took to the streets in 10 cities across the country to protest against the high cost of living, including more than 50,000 in downtown Tel Aviv. The demonstrators rallied in support of hundreds of people who have set up protest camps against the government's economic and social policies. (Photo by Uriel Sinai/Getty Images)

People wrapped in blankets sit on the road as they are evacuated from a hotel after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo April 14, 2016. A powerful earthquake with a magnitude of 6.5 knocked over buildings in southern Japan on Thursday evening, and police said people may be trapped underneath. (Photo by Reuters/Kyodo News)