Joe Deedon, president of TAC ONE Consulting, demonstrates searching for a shooter in a middle school during an Active Shooter Response course offered by TAC ONE in Denver April 2, 2016. According to TAC ONE, the course, which is offered for the first time to concealed weapons permit carrying civilians, is designed at preparing people to effectively save lives prior to the arrival of law enforcement at an active shooter incident. (Photo by Rick Wilking/Reuters)

A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

A dog from the K9 Division of the Sri Lanka Army’s Commando Regiment performs during an event to mark International Children’s Day at a school in Welisara, Colombo, Sri Lanka, 01 October 2016. Sri Lanka marks the Children's Day on 01 October with more emphasis on prevention of child abuse. (Photo by M.A. Pushpa Kumara/EPA)

Buses are stranded in a flooded street in Fuzhou, Fujian province, July 24, 2014. Typhoon Matmo hit Taiwan on Wednesday, bringing heavy rain and strong winds, shutting financial markets and schools. It passed the island and headed into China, downgraded from typhoon to tropical storm. (Photo by Reuters/Stringer)

A sculptural artwork depicting former Chilean dictator Augusto Pinochet and headless presidents shot by a hooded high school student (not pictured) is seen at the Contemporary Art Museum in Santiago, December 2, 2014. The artwork, part of the “El ladrillo angular” (The angular brick) exhibition, portrays a student fighting against the ongoing continuity of dictatorship because of a political and economic system which has been impossible to destroy, according to “Papas Fritas” the artwork's creator. (Photo by Ivan Alvarado/Reuters)

Del Mar firefighters roll up hose after a day fighting wildfires Wednesday, May 14, 2014, in Carlsbad, Calif. More wildfires broke out Wednesday in San Diego County, threatening homes in Carlsbad and forcing the evacuations of military housing and an elementary school at Camp Pendleton. (Photo by AP Photo)

A woman dances during a rehearsal by the group “Tambores de Olokun” in Rio de Janeiro, Brazil, Sunday, April 17, 2022. The Brazilian municipalities of Rio de Janeiro and Sao Paulo postponed the traditional parades of the carnival samba schools to April 22 - 23, as a result of the COVID-19 pandemic. (Photo by Bruna Prado/AP Photo)

A member of Viradouro samba school performs during the first night of Rio's Carnival parade at the Sambadrome Marques de Sapucai in Rio de Janeiro, Brazil on April 22, 2022. (Photo by Carl de Souza/AFP Photo)