Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)

Protesters clad in improvised protective gear prepare for a clash with police in central Kiev, Ukraine, Monday, January 20, 2014. After a night of vicious streets battles, anti-government protesters and police clashed anew Monday in the Ukrainian capital Kiev. (Photo by Evgeny Feldman/AP Photo)

A rusty revolver is seen near the body of a man, who police said was killed by police operatives, and two sachets of “Shabu” or methampethamine chloride were found on his pockets in Manila, Philippines August 17, 2017. (Photo by Erik De Castro/Reuters)

A police officer escorts a civilian away from the scene of a shooting, Sunday, July 22, 2018, in Toronto, Canada. A gunman opened fire in central Toronto on Sunday night, injuring 13 people including a child. Two dead including gunman, police reported. (Photo by Frank Gunn/The Canadian Press via AP Photo)

An armed man gestures in front of the police headquarters in Slaviansk, April 12, 2014. At least 20 armed militants wearing mismatched camouflage outfits took over the police and security services headquarters in the eastern city of Slaviansk seizing hundreds of handguns. (Photo by Gleb Garanich/Reuters)

A mob attacks a female police officer accused of shooting a protester in the Buterere neighborhood of Bujumbura, Burundi, May 12, 2015. Protesters opposed to the president's decision to run for a third term chased, beat and stoned the woman, who was later handed back to the police. (Photo by Goran Tomasevic/Reuters)

A gun is seen next to the body of a man was killed in a shootout with police in Manila, Philippines early October 21, 2016. According to the police, sachets containing substance believed to be drug shabu (Methamphetamine Hydrochloride) were found in the killed man's pockets. (Photo by Damir Sagolj/Reuters)

Nepalese police officers worship a dog during the dog festival as part of Tihar celebrations, also called Diwali, at the Central Police Dog Training School in Kathmandu, Nepal October 29, 2016. Dogs are worshipped to acknowledge their role in providing security during Tihar festival, one of the most important Hindu festivals that is also dedicated to the worship of the goddess of wealth Laxmi. (Photo by Navesh Chitrakar/Reuters)