A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

A tornado builds and travels southwest causing damage near Dean Rd. and 82nd Avenue in Hutchinson, Kan. on Monday, July 13, 2015. (Photo by Sandra J. Milburn/The Hutchinson News via AP Photo)

Mount Sinabung is seen during an eruption from Surbakti village in Karo, North Sumatra, Indonesia, April 20, 2015. The local government is preparing the relocation of residents from three of the villages that were destroyed. (Photo by Tibta Pangin/Getty Images/Anadolu Agency)

In this Saturday, September 5, 2015, photo, three women in costumes look at sea life swimming above them during a private party held at the Georgia Aquarium as part of Dragon Con in Atlanta. The convention draws fans from around the country to take part in sci-fi and fantasy costume contests, a massive parade through downtown Atlanta and educational seminars about science and costume making. (Photo by Ron Harris/AP Photo)

A man holds a child after rescuing him from a kindergarten affected by a fire at a commercial building, in Ningde, Fujian province, China, September 16, 2015. According to local media, more than 260 people were evacuated due to the fire, which broke out Wednesday morning. No causalities have been reported and the cause of it is still unknown. (Photo by Reuters/China Daily)

Ethnic Miao men wearing traditional masks smear dust on a woman's face to wish her good luck during local celebration event for Lunar New Year in Liuzhou, Guangxi Zhuang Autonomous Region, China, February 16, 2016. (Photo by Reuters/Stringer)

A woman made up as a skull participates in Day of the Dead festivities in Mexico City, Thursday, October 27, 2016. The holiday honors the dead as friends and families gather in cemeteries to decorate their loved ones' graves and hold vigil through the night on Nov. 1 and 2. (Photo by Marco Ugarte/AP Photo)

Bikini-clad women ski as they are led by a car during a performance on the frozen Yenisei River outside Krasnoyarsk, Siberia, Russia, March 20, 2016. The performance, entitled “Siberian Spring's Strings” and created with the participation of artist Vasily Slonov, marked the day of spring equinox (vernal equinox), according to organizers. (Photo by Ilya Naymushin/Reuters)