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 bakery worker rides a bicycle as he carries fresh bread on his head in Cairo, Egypt, February 9, 2016. (Photo by Asmaa Waguih/Reuters)

A couple stands next to a poster depicting Dutch politician Geert Wilders and Russian President Vladimir Putin kissing, at a metro station in Amsterdam April 3, 2016. (Photo by Cris Toala Olivares/Reuters)

A farmer harvests broccoli in the town of al-Ansariyeh south of Sidon, Lebanon March 15, 2016. (Photo by Ali Hashisho/Reuters)

A woman and a child make a bonfire at a makeshift camp for migrants and refugees at the Greek-Macedonian border near the village of Idomeni, Greece, April 1, 2016. (Photo by Marko Djurica/Reuters)

A Bengal cat is seen during the Mediterranean Winner 2016 cat show in Rome, Italy, April 3, 2016. (Photo by Max Rossi/Reuters)

Actress Ruby Rose, left, recipient of the Stephen F. Kolzak Award, hands her jacket to presenter Taylor Swift during the 27th Annual GLAAD Media Awards at the Beverly Hilton on Saturday, April 2, 2016, in Beverly Hills, Calif. (Photo by Chris Pizzello/Invision/AP Photo)

In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)