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)

Members of the Communist New Fourth Army on parade. Note how the modern equipment contrasts with the shoeless soldiers in the foreground. (Photo by Hulton Archive/Getty Images). 6th July 1946

A woman wearing a protective mask walks outside a village that was placed under lockdown due to the number of COVID-19 cases among residents in Manila, Philippines on Thursday, March 11, 2021. The Philippine capital placed two villages and two hotels on lockdown Thursday and police have renewed warnings against kissing and other “public display of affection” after a new surge in coronavirus infections. (Photo by Aaron Favila/AP Photo)

The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

Documenting the effects of climate change first hand over the past eight years, Camille Seaman fears we may be on the road to the last iceberg. Photographing the enormous frozen floats at both poles for the past eight years, the Californian adventurer has seen the receding ice shelves and experienced the changing warmer weather. Feeling that her intimate and emotional work documents a snapshot of history, Camille presents her series “The Last Iceberg” as a study of what she sees as the personality of each huge iceberg. Drawing parallels with the famous novel, “The Last of the Mohicans”, Camille, 42, wonders whether these unique, almost alien natural features will become a thing of the past or part of nature's renewal process. (Photo by Camille Seaman/Barcroft Media)

“Basunga”. Basunga (3 weeks-old newborn with albinism) is happily sleeping with his cousin. For now, he does not yet realize the difficulties he will face to integrate into the Congolese society as a PWA. The success of his integration will greatly depends of how he accepts himself and his skin condition a and how educated he will be. Photo location: Kinshasa, Congo RDC. (Photo and caption by Patricia Willocq/National Geographic Photo Contest)

The Baby Nager dragon, from DreamWorks’ new “How to Train Your Dragon” Live Spectacular touring musical, shows off it’s colors outside of the New York Public Library. (Photo by Mark Von Holden)