Police officers escort people from inside the shopping center as they respond to a shooting at the Olympia Einkaufzentrum (OEZ) at July 22, 2016 in Munich, Germany. According to reports, several people have been killed and an unknown number injured in a shooting at a shopping centre in the north-western Moosach district in Munich. Police are hunting the attacker or attackers who are thought to be still at large. (Photo by Joerg Koch/Getty Images)

Miniature spring-wound 35-mm film camera in a modified cigarette pack. The Tessina’s small size and quiet operation provided more options for concealment than most commercially available models. (Photo by Central Intelligence Agency)

Members of the U.S. Army 173rd Airborne Brigade stand at attention as a Ukrainian folk dance group performs at the opening ceremony of the “Rapid Trident” NATO military exercises on September 15, 2014 near Yavorov, Ukraine. The two-week exercises include participating units from a variety of NATO and NATO-associate countries as well as Ukrainian troops. Meanwhile fighting between pro-Russian separatists and Ukrainian armed foces has flared again in eastern Ukraine in a battle for the control of Donetsk airport despite the tenuous ceasefire. (Photo by Sean Gallup/Getty Images)

People look at French artist Clement Briend's photographic light installation “Divine Trees”, which features images of divine figures highly revered in Asian cultures projected on trees towering over bystanders, during a media preview of the Singapore Night Festival in Singapore August 21, 2014. The Singapore Night Festival begins on Friday. (Photo by Edgar Su/Reuters)

Members of the Times Square Alliance snow clearing team take a photo on a snowbank at Times Square in the Manhattan borough of New York January 23, 2016. A winter storm dumped nearly 2 feet (58 cm) of snow on the suburbs of Washington, D.C., on Saturday before moving on to Philadelphia and New York, paralyzing road, rail and airline travel along the U.S. East Coast. (Photo by Shannon Stapleton/Reuters)

Members of the “Exit Point” amateur rope-jumping group stage a performance as they jump from a 44-metre high (144-ft) waterpipe bridge in the Siberian Taiga area outside Krasnoyarsk, November 3, 2013. Fans of rope-jumping, a kind of extreme sport involving a jump from a high point using an advanced leverage system combining mountaineering and rope safety equipment, marked the end of the group's jumping season and recent Halloween festivities. (Photo by Ilya Naymushin/Reuters)

Models promote a condom brand at the first Shenzhen s*x Culture Festival on September 21, 2007 in Shenzhen of Guangdong Province, China. The festival aims to increase awareness about reproductive health and popularise s*x education. (Photo by China Photos/Getty Images)

Number 10. BELL H-13 SIOUX was a two-bladed, single engine, light helicopter built by Bell Helicopter. Westland Aircraft manufactured the Sioux under license for the British military as the Sioux AH.1 and HT. In 1947, the United States Air Force ordered the improved Bell Model 47A. Most were designated YR-13 and three winterized versions were designated YR-13A. The United States Army first ordered Bell 47s in 1948 under the designation H-13. These would later receive the name Sioux. The Bell-built H-13 B is seen airborne in this April 29, 1951 photo. The helicopter is equipped with a 173 horsepower engine, cruises at 85 miles per hour, climbs 900 feet in a minute and has a service ceiling of 11,500 feet. (Photo by AP Photo)