A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut. A man killed his mother at their home and then opened fire inside the elementary school where she taught, massacring 26 people, including 20 children, as youngsters cowered in fear to the sound of gunshots reverberating through the building and screams echoing over the intercom. (Photo by Jessica Hill/Associated Press)

Seized plastic handguns which were created using 3D printing technology are displayed at Kanagawa police station in Yokohama, south of Tokyo, in this photo taken by Kyodo May 8, 2014. Yoshimoto Imura became the first man to be arrested in Japan for illegal possession of two guns he created himself using 3D printing technology, Japanese media said on Thursday. The 27-year-old, a college employee in the city of Kawasaki, was arrested after police found video online posted by Imura claiming to have produced his own guns. Gun possession is strictly regulated in Japan. Police raided Imura's home and found five guns, two of which could fire real bullets, Japanese media said. (Photo by Reuters/Kyodo)

Arnaq Egede walks to the potato field on her family's farm on July 31, 2013 in Qaqortoq, Greenland. The farm, the largest in Greenland, has seen an extended crop growing season due to climate change. (Photo by Joe Raedle/Getty Images)

A woman carrying a basket of papayas while walking through a vegetable market in Bangkok, Thailand November 11, 2011. (Photo by Kerek Wongsa/Reuters)

Playboy Bunny, Penny (surname not given), is helped into her costume as she prepares herself before starting work at the Playboy Club on July 26, 2016 in London, England. The Playboy Club London is celebrating its 50th anniversary this year and will mark the event with a “Touch of Gold” party on July 29. (Photo by Carl Court/Getty Images)

Georgian men take a break from selling fruit and vegetable at a street market in Tbilisi, Georgia, Wednesday, July 20, 2016. (Photo by Shakh Aivazov/AP Photo)

A Thai traffic security guard wears a Santa Claus costume as he directs the traffic on a street during Christmas celebrations outside a shopping mall in Bangkok, Thailand, 22 December 2015. The campaign of a shopping mall is held to celebrate the upcoming Christmas season and to attract shoppers. (Photo by Narong Sangnak/EPA)

A man takes a selfie next to a flooded street due to the overflowing of the Mapocho river during heavy rains in Santiago on April 17, 2016. Four million people in Santiago were without tap water Sunday after unusually heavy rain pounding central Chile triggered landslides that fouled the city's water supply and forced the closure of the world's biggest copper mine, officials said. (Photo by Martin Bernetti/AFP Photo)