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)

A Hong Kong Correctional Services Dog Unit (CSDU) officer demonstrates training at the CSDU training facility in Stanley, Hong Kong, China, 27 February 2018. The Hong Kong CSDU consists of 29 staff members divided across six dog teams. According to the department's latest figure from 2017, the average daily penal population of Hong Kong was 8,529. (Photo by Jérôme Favre/EPA/EFE)

Model Alessandra Ambrosio is seen at Coachella Music & Arts Festival at the Empire Polo Club on Friday, April 14, 2017, in Indio, Calif. (Photo by Hollywood To You/Star Max/GC Images)

Dancers wait at backstage as they prepare for a dance performance during the Bali Arts Festival in Bali, Indonesia, Wednesday, June 21, 2017. The resort island of Bali is holding a month-long annual Bali Arts Festival from June 10 to July 8. (Photo by Firdia Lisnawati/AP Photo)

A woman sits in a cell at the Los Angeles County Women's jail in Lynwood, California April 26, 2013. (Photo by Lucy Nicholson/Reuters)

Members of the Knights Guard clean the ice during the Vegas Golden Knights' game against the Anaheim Ducks at T-Mobile Arena on January 14, 2021 in Las Vegas, Nevada. The Golden Knights defeated the Ducks 5-2. (Photo by Ethan Miller/Getty images/Profimedia)

A man is silhouetted in front of the Allianz-Arena as he walks his dogs at sunrise in Munich, southern Germany, Friday, April 10, 2015. (Photo by Peter Kneffel/AP Photo/DPA)

A coil-shaped Helix Nebula showing a fine web of filamentary “bicycle-spoke” features embedded in the colorful red and blue ring of gas. At 650 light-years away, the Helix is one of the nearest planetary nebulae to Earth. A planetary nebula is the glowing gas around a dying, Sun-like star. (Photo by Reuters/NASA)