School teachers and staff members take part during an active shooter training at James I. O'Neill High School in Highland Falls, New York, U.S., December 12, 2017. (Photo by Eduardo Munoz/Reuters)

Two and a half year-old Jennifer Martin in tears during a visit to Santa at Harrods department store in London, 10th December 1949. (Photo by William Vanderson/Fox Photos/Hulton Archive/Getty Images)

A boy listens to a prayer before he and other relatives visit the grave of their loved ones, all minors, who were killed a year ago during the government's war on drugs campaign, at the Tala Cemetery in Caloocan, east of Manila on December 28, 2017, as the world commemorates Holy Innocents' Day. Catholics celebrate the biblical passage when King Herodes the great ordered to kill all newborn babies to kill Jesus Christ. (Photo by Noel Celis/AFP Photo)

The competition is run by Royal Observatory Greenwich sponsored by Insight Investment and in association with BBC Sky at Night Magazine. This year astrophotographers from 91 countries sent in more than 4,200 spectacular entries. Here: The Milky Way rises above an isolated lighthouse in Tasmania. Shot by James Stone of Australia. (Photo by James Stone/Astronomy Photographer of the Year 2018)

North Korea's Samjiyon Orchestra performs at Pyongyang Grand Theatre in Pyongyang, North Korea, September 18, 2018. (Photo by Pyeongyang Press Corps/Pool via Reuters)

A Russian army conscript called up for service in the Kremlin regiment and a woman say farewell at Yekaterinburg-Passazhirsky railway station in Yekaterinburg, Russia on November 15, 2018. (Photo by Donat Sorokin/TASS Russian News Agency)

Venezuelan artist Deborah Castillo licks the boots of a man dressed as a member of the military during her performance “Lamebrasil, Lamezuela – questioning power in Latin America”, in Sao Paulo, Brazil, March 24, 2019. (Photo by Amanda Perobell/Reuters)

A Palestinian woman reacts after inhaling tear gas fired by Israeli forces during a protest marking Land Day and the first anniversary of a surge of border protests, at the Israel-Gaza border fence, in the southern Gaza Strip on March 30, 2019. (Photo by Ashraf Abu Amrah/Reuters)