An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

Cars at a car dealership are seen in the flooded village of Fischerdorf, near Deggendorf June 7, 2013. REUTERS/Michaela Rehle

A Salvadorean clown going by the name of “Almohadita” poses during National Clown Day celebrations at Beethoven Square in San Salvador December 3, 2014. The Salvadorean congress declared the second Wednesday of December as National Clown Day to honour all Salvadorean clowns in their efforts to bring fun to the country, reported local media. (Photo by Jose Cabezas/Reuters)

An Orthodox activist (Right) clashes with a gay rights campaigner during a protest outside of the State Duma, Russian Parliament's lower chamber, in downtown Moscow, January 22, 2013. (Photo by Ilya Pitalev/RIA Novosti)

Riot police stood by the gates of parliament in Nairobi, Kenya, Tuesday, May 14, 2013, during a demonstration against members of parliament who demanded higher wages. Demonstrators released two dozen piglets and poured blood on the pavement to protest the demands for a wage hike. (Photo by Carl de Souza/AFP Photo)

The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

A large storm cloud covers the Sydney CBD on March 5, 2014 in Sydney, Australia. A severe thunderstorm warning was issued for the Sydney metropolitan area late this afternoon with heavy rainfall due to cause flash flooding in areas. (Photo by Cassie Trotter/Getty Images)

Nora Muaid stands in Zawraa Park on December 2, 2011 in Baghdad, Iraq. The park's 180-foot tall Ferris wheel opened earlier this year and is the second largest in the Middle East. (Photo by Mario Tama/Getty Images)