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)

Revellers pose during the 24th Street Parade dance music event in Zurich, August 29, 2015. (Photo by Arnd Wiegmann/Reuters)

A street entertainer waits for tourists in Havana, Cuba on October 2009. (Photo by Desmond Boylan/Reuters)

Street animators wearing fancy costumes take a break on a bench in a park in Stavropol, Russia on March 14, 2021. (Photo by Eduard Korniyenko/Reuters)

Children play with their pet Hamster at a street in Kochi on March 29, 2021. (Photo by Arun Sankar/AFP Photo)

Chrissy Teigen and daughter Luna Stephens seen on the streets of Manhattan on June 24, 2019 in New York City. (Photo by James Devaney/GC Images)

A girl plays in a waterlogged street following a heavy monsoon rainfall in Mumbai on June 9, 2021. (Photo by Sujit Jaiswal/AFP Photo)

Four men dressed as zombies participate in a Zombie Walk procession in the streets of Paris October 12, 2013. (Photo by Benoit Tessier/Reuters)