In this handout image provided by the Police of Swiss canton Valais the wreckage of a bus is seen after it crashed inside a motorway tunnel on March 13, 2012 in Sierre, Switzerland. 28 people, including 22 children, returning from a skiing holiday died in this bus accident. (Photo by Police Cantonale Valaisanne via Getty Images)

South Korean police officers show their martial arts' skills during the official launch ceremony of the 2012 Seoul Nuclear Security Summit on February 15, 2012 in Seoul, South Korea. The Korean National Police Agency launched a security squad, exclusively established for the successful hosting of the 2012 Seoul Nuclear Security Summit. The 2012 Seoul Nuclear Security Summit will be held in Seoul from March 26-27, 2012. (Photo by Chung Sung-Jun/Getty Images)

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)

A police officer reacts to flames during a protest against Chile's government in Santiago, Chile on November 4, 2019. Unrest began in Chile last October 18 with protests against a rise in transport tickets and other austerity measures and descended into vandalism, looting, and clashes between demonstrators and police. Protesters are angry about low salaries and pensions, poor public healthcare and education, and a yawning gap between rich and poor. (Photo by Henry Romero/Reuters)

Police dog handlers wait outside the Loftus Road stadium after FA Cup Fourth Round between Queens Park Rangers and Chelsea on January 28, 2012 in London, England. Security has been stepped up after QPR player Anton Ferdinand recieved a package containing a bullet. (Photo by Dan Kitwood/Getty Images)

Relatives of a missing person scuffle with police officers on the bank of the Yangtze River, near Jingjiang, Jiangsu province January 17, 2015. A search and rescue operation was still underway after the boat capsized on January 15, leaving 22 people missing, including foreigners. (Photo by Aly Song/Reuters)

Indian police women take part in a full dress rehearsal for the Republic Day parade in Srinagar January 24, 2015. India will celebrate its annual Republic Day on Monday. (Photo by Danish Ismail/Reuters)

Women take a selfie next to a police officer as they take part in New Year's Eve celebrations in the Bund, in Shanghai, China December 31, 2016. (Photo by Aly Song/Reuters)