A visitor looks at a sculpture entitled “Couple Under an Umbrella, 2013” by artist Ron Mueck during the press day for his exhibition at the Fondation Cartier pour l'art contemporain in Paris April 15, 2013. (Photo by Charles Platiau/Reuters)

This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

A man shows medicine to an Indian policeman after he was stopped by the police during a curfew in Srinagar July 15, 2016. Curfew imposed in the disputed Himalayan region continued for the seventh straight day to check anti-India violence following the recent killing of a charismatic Kashmiri insurgent Burhan Wani. (Photo by Danish Ismail/Reuters)

A World War II era P-51 Mustang fighter plane stands in front of a modern 747-8 freighter and a 757 passenger jet at The Boeing Company's centennial celebration in Renton, Washington, U.S. July 15, 2016. (Photo by Alwyn Scott/Reuters)

New Orleans police officers try to keep their heads down as they move in on a Black Panther headquarters during an exchange of gunfire in New Orleans on September 15, 1970. The shootout occurred as police moved in to make arrests on Tuesday morning following a series of incidents. (Photo by Jack Thornell/AP Photo)

Indonesian students go to school via a makeshift suspension bridge in Ngemplak, Boyolali regency, Indonesia on November 15, 2017. The lack of access to roads makes students every day to cross the dangerous waterways to go to school. (Photo by Arief Setiadi/Pacific Press/Barcroft Images)

A Tamil devotee prays during the Thai Pongal harvest festival at a temple in Colombo January 15, 2016.The Tamil festival of Thai Pongal is a thanksgiving ceremony in which the farmers thank the spirits of nature, the sun and the farm animals for their assistance in providing a successful harvest. (Photo by Dinuka Liyanawatte/Reuters)

North Korean women soldiers take part in a military parade Saturday, April 15, 2017, in Pyongyang, North Korea, to celebrate the 105th birth anniversary of Kim Il Sung, the country's late founder and grandfather of current ruler Kim Jong Un. (Photo by Wong Maye-E/AP Photo)