Injured horses huddle together in Oklahoma City on Monday. (Photo by Chris Landsberger/The Oklahoman)

In this Wednesday, July 13, 2016, handout image provided by Solar Impulse, the Solar Impulse 2 flying over the pyramids, Egypt Cairo. The experimental solar-powered airplane has arrived in Egypt as part of its global voyage. (Photo by Jean Revillard, Rezo via the AP Photo)

Soldiers use electronic sensors to search for missing firefighters under a line of fire trucks caught in massive gas explosions in Kaohsiung, Taiwan, Friday, August 1, 2014. A series of underground explosions about midnight Thursday and early Friday ripped through Taiwan's second-largest city, killing scores of people, Taiwan's National Fire Agency said Friday. (Photo by Wally Santana/AP Photo)

An East German civilian (L) shows an East German customs officer the contents of his Trabant (auto) at checkpoint Potsdamer Platz in East Berlin in this November 24, 1989 file picture, as East Germany enforcing stringent customs controls to avoid smuggling. (Photo by Reuters)

Maj. Matt O'Donnell of Glenelg, MD shields himself from rotor wash as Ospreys carrying the delegation of U.S. Secretary of Defense Leon Panetta leaves on March 14, 2012 at Forward Operating Base Shukvani, Afghanistan. Panetta is also scheduled to meet with President Karzai during his two-day visit to Afghanistan. The trip comes as the Taliban has vowed revenge following this past weekend's killing spree by a U.S. soldier who is accused of killing 16 civilians in Afghanistan. Most of those killed were children and women. (Photo by Scott Olson/Getty Images)

Second placed Kalex Moto2 Tito Rabat (rear R) of Spain and third placed Kalex Moto2 Alex Rins of Spain spray with champagne during the award ceremony for the Czech Grand Prix in Brno, Czech Republic, August 16, 2015. (Photo by David W. Cerny/Reuters)

The Soyuz TMA-11M capsule with the International Space Station (ISS) crew members Japanese astronaut Koichi Wakata, Russian cosmonaut Mikhail Tyurin and U.S. astronaut Rick Mastracchio lands south-east of the town of Dzhezkazgan in central Kazakhstan, May 14, 2014. The first Japanese to command a space mission and crewmates from the United States and Russia landed safely in Kazakhstan on Wednesday, wrapping up a 188-day stay aboard the International Space Station. (Photo by Dmitry Lovetsky/Reuters)

Police officers clear the area near Borough market at London Bridge on June 3, 2017 in London, England. Police have responded to reports of a van hitting pedestrians on London Bridge in central London. (Photo by Dan Kitwood/Getty Images)