People dance Tuesday, April 28, 2015, in Baltimore. Maryland's governor vowed there would be no repeat of the looting, arson and vandalism that erupted Monday in some of the city's poorest neighborhoods. (Photo by Matt Rourke/AP Photo)

Firefighters attempt to put out a fire at an abandoned building with the protection of St. Louis City Police in St. Louis, Missouri August 19, 2015. Police fatally shot a black man they say pointed a gun at them, drawing angry crowds and recalling the racial tensions sparked by the killing of an unarmed African-American teen in nearby Ferguson, Missouri, just over a year ago. (Photo by Lawrence Bryant/Reuters)

This combination of August 30, 2005 and July 29, 2015 aerial photos shows downtown New Orleans and the Superdome flooded by Hurricane Katrina and the same area a decade later. Katrina's powerful winds and driving rain bore down on Louisiana on August 29, 2005. The storm caused major damage to the Gulf Coast from Texas to central Florida while powering a storm surge that breached the system of levees that were built to protect New Orleans from flooding. (Photo by David J. Phillip/Gerald Herbert/AP Photo)

Laura Halford of Wales jumps during her hoop routine as she competes in the rhythmic gymnastics individual all-around final event at the 2014 Commonwealth Games in Glasgow, Scotland, July 25, 2014. (Photo by Phil Noble/Reuters)

Businesswoman and vendor Sonia Maria Paypay sells clothing at a stand at the commercial zone of Gamarra in Lima, April 16, 2015. (Photo by Mariana Bazo/Reuters)

Confiscated rare and protected wildlife products such as these stuffed Sumatran tiger skins are burned and destroyed during a ceremony by government forestry and wildlife officials in Banda Aceh, Aceh province, Indonesia May 23, 2016 in this photo taken by Antara Foto. (Photo by Irwansyah Putra/Reuters/Antara Foto)

This photo provided by Netflix/naturepl.com and WWF-International shows an African Elephant (Loxodonta africana) in front of double rainbow, in Masai Mara, Kenya, included in the Netflix natural history series, “Our Planet”, in collaboration with Silverback Films and WWF. The eight-part series debuts in 2019. (Photo by Andy Rouse/Naturepl/WWF-International/Netflix via AP Photo)

Sunday night, Lauren Watts searches for her dog in Mayflower, Arkansas., after a tornado struck the town. (Photo by Benjamin Krain/The Arkansas Democrat-Gazette)