Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

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)

Trainer Lawney Hill poses for a photograph as she wears tights over her face to keep out the cold after taking her horses out on the all-weather gallops in Tetsworth, Britain, March 2, 2018. (Photo by Eddie Keogh/Reuters)

An Indian lift operator stands inside a dedicated lift for people suspected to be infected with the new corona virus at the Government Gandhi Hospital in Hyderabad, India, Monday, March 2, 2020. Coronavirus has spread to more than 60 countries, and more than 3,000 people have died from the COVID-19 illness it causes. (Photo by Mahesh Kumar A./AP Photo)

Rachel Miner, 15, left, of Emmetsburg, Iowa, sits with Carlotta Haas, 15, a foreign exchange student from Duesseldorf, Germany, who had been living with Miner and her family but was called home, as they waited for her flight Wednesday, March 25, 2020, in at Minneapolis-St. Paul International Airport in Minneapolis. (Photo by Anthony Souffle/Star Tribune via AP Photo)

Deaf and hard of hearing people perform a Buddhist Guanyin Thousand Hand dance to mark Sunday's National Day for Helping the Disabled in Yunnan, Kunming province, China on May 19, 2018. (Photo by Wong Campion/Reuters)

University students demonstrate against the crisis in the public education, budget cuts and a tax reform project announced by the government of Ivan Duque in Medellin, Colombia on December 13, 2018. (Photo by Joaquín Sarmiento/AFP Photo)

A member of the Qinghai Acrobatic Troupe checks her hair with a smartphone during a media preview for the world premiere of cabaret show “Shanghai Mimi” as part of Sydney Festival in Chinatown, central Sydney, Australia, 08 January 2019. Sydney Festival 2019 runs from 09 to 27 January and will feature theatre, dance, circus, music, visual arts and talks from international and local artists. (Photo by Steven Saphore/EPA/EFE)