A demonstrator is detained by police officers during clashes in downtown Barcelona, Spain, Friday, October 30, 2020. Clashes have erupted in a central Barcelona square between anti-riot police and hundreds who had gathered to protest the mandatory closure of bars, restaurants and other businesses in the latest effort to rein in on coronavirus outbreaks. (Photo by Joan Mateu/AP Photo)

Police walk past a burning car during riots in Birmingham City Centre on August 8, 2011 in Birmingham, England. After three nights of rioting and looting in and around London, the chaos is starting to spread to other cities around Britain. (Photo by Jeff J Mitchell/Getty Images)

A refugee sits in front of a Greek riot police cordon during a protest at the Greek-Macedonian border, near the Greek village of Idomeni, March 1, 2016. (Photo by Alexandros Avramidis/Reuters)

A police officer lies on the street after being run over by a bus during a protest against the increase in the price of public transport in San Cristobal, Venezuela March 29, 2016. (Photo by Carlos Eduardo Ramirez/Reuters)

A student protester throws a stone against a riot police vehicle during a demonstration to demand changes in the education system in Santiago, Chile, April 21, 2016. (Photo by Ivan Alvarado/Reuters)

A demonstrator kicks a riot police vehicle during an unauthorized march called by the Chilean student federations to protest against government's education reform, in Santiago, Chile July 5, 2016. (Photo by Ivan Alvarado/Reuters)

A traffic police officer directs vehicles at a street junction during sunset in Pyongyang, North Korea, Thursday, August 25, 2016. (Photo by Dita Alangkara/AP Photo)

Riot police fire tear gas during a protest by supporters of Dilma Rousseff in Sao Paulo, Brazil August 31, 2016. (Photo by Paulo Whitaker/Reuters)