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)

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 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)

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)

Cosplayer Monzerath Gutierrez, who portrays Dragon Ball Z character Trunks, female version, poses for a portrait during the 4th edition of the MiniCon Anime convention, at the School of Dance, in Managua, Nicaragua, Sunday, July, 26, 2015. (Photo by Esteban Felix/AP Photo)

A member of Brazilian samba school “Aguia de Ouro” takes part in a parade at Anhembi sambadrome as part of carnival in Sao Paulo, Brazil, early 25 February 2017. The Sao Paulo Carnival runs from 24 to 28 february 2017. (Photo by Fernando Bizerra Jr./EPA)

Dan Copeland, left, and Alex Morneau of Biddeford, Maine, former high school cheerleaders, perform back flips while enjoying the record breaking heat, Thursday, May 18, 2017, at Old Orchard Beach, Maine. The temperature climbed well into the 90s in many locations throughout the state. (Photo by Robert F. Bukaty/AP Photo)

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)