A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

Riot police walk in the street as a couple kiss on June 15, 2011 in Vancouver, Canada. Vancouver broke out in riots after their hockey team the Vancouver Canucks lost in Game Seven of the Stanley Cup Finals. (Photo by Rich Lam/Getty Images)

Police academy graduates march during their graduation ceremony in Islamabad, Pakistan May 18, 2015. Out of the 408 graduating officers, 76 female officers were inducted into the Pakistan police force, according to the police force. (Photo by Caren Firouz/Reuters)

Leaves and forest foliage claim abandoned motors at makeshift car graveyards. German photographer Dieter Klein travels the world to find vintage automobiles left to rust in leafy forests and fields. Here: Seemingly camouflaged cars are stacked on top of each other causing them to blend in with the landscape, in 2013, France. (Photo by Dieter Klein/Barcroft Media)

New autopilot features are demonstrated in a Tesla Model S during a Tesla event in Palo Alto, California, 2015. Federal officials say the driver of a Tesla S sports car using the vehicle’s “autopilot” automated driving system has been killed in a collision with a truck, the first U.S. self-driving car fatality. The National Highway Traffic Safety Administration said preliminary reports indicate the crash occurred when a tractor-trailer made a left turn in front of the Tesla at a highway intersection. Joshua D. Brown, of Canton, Ohio, died in the accident May 7 in Williston, Florida, when his car's cameras failed to distinguish the white side of a turning tractor-trailer from a brightly lit sky and didn't automatically activate its brakes, according to government records obtained Thursday. (Photo by Beck Diefenbach/Reuters)

Troops of the Interior Ministry take part in a parade during a ceremony marking the Iraqi Police Day at a police academy in Baghdad January 9, 2016. (Photo by Khalid al Mousily/Reuters)

A member of a female grappling team from Qinghai Province armed police undergoes dagger exercise on August 8, 2006 in Xining of Qinghai Province, China. The female grappling team, established in May 2006, has 40 women soldiers aged 18 to 21. The training program includes grappling, boxing, dagger exercise and shooting. (Photo by China Photos). P.S. All pictures are presented in high resolution.

Egyptian riot police charge towards protesters near Egypt's Interior Ministry, as violent demonstrations continued into their second day on February 3, 2012 in central Cairo, Egypt. (Photo by Ed Giles/Getty Images)