People sit on the top of a truck heavily piled with corn-stalks plies as they head for Mogadishu from Afgooye on October 19, 2016. At least four police officers were killed on October 18 when a suicide bomb attacker rammed an explosives-packed car into a police station before fighters from the Al-Qaeda-linked Shabaab group subsequently stormed the area killing at least 10 people, including soldiers and civilians. (Photo by Mohamed Abdiwahab/AFP Photo)

A firefighter carries a woman from her car after it was caught in street flooding as a powerful storm moves across Southern California on February 17, 2017 in Sun Valley, California. After years of severe drought, heavy winter rains have come to the state, and with them, the issuance of flash flood watches in Santa Barbara, Ventura and Los Angeles counties, and the evacuation of hundreds of residents from Duarte, California for fear of flash flooding from areas denuded by a wildfire last year. (Photo by David McNew/Getty Images)

In this March 22, 1975 file photo, a refugee clutches a baby as a government helicopter gunship carries them away near Tuy Hoa, Vietnam, 235 miles northeast of Saigon. They were among thousands fleeing from Communist advances. AP Photographer Nick Ut will be retiring from the AP in March 2017 after 51 years of taking photographs from the front lines of the Vietnam War to the red carpets of Hollywood. (Photo by Nick Ut/AP Photo)

Winner. “I took this picture of a woman in traditional clothing in Cartagena, Colombia”. PAUL GOLDSTEIN, JUDGE: “The blaze of colour from every angle, the boldness of the picture, taken from behind, which gives it so much more allure and frankly a superb get up. Did I mention the colours? Oh, and that looks suspiciously like a Nokia”. (Photo by Stanislav Shmelev/The Guardian)

A Bosnian special forces soldier returns fire 06 April 1992 downtown Sarajevo as he and civilians come under fire from Serbian snipers. The Serb extremists were shooting from the roof of a hotel at a peace demonstration of some of 30,000 people as fighting between Bosnian and Serb fighters escalated in the capital of Bosnia- Hercegovina. (Photo by Mike Persson/AFP Photo)

A huge supercell dominates the Texas skyline like an atomic bomb explosion on April 11, 2015 in Lubbock, Texas. A huge supercell dominates the Texas skyline like an atomic bomb explosion. These incredible images were taken on April 11th, by photographer Darin Kuntz who has spent in his entire life in so-called Tornado Alley. And Darin confirmed that he snapped the storm standing in his backyard in Lubbock, Texas. (Photo by Darin Kuntz/Barcroft Media)

Student protestors, including one girl with a camera, struggle with soldiers from the Chinese Army, the PLA. Tiananmen Square, 1989. (Photo by Jeff Widener/Associated Press)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)