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)

A Hindu devotee lies on the banks of river Ganges she worships the Sun god during the religious festival of Chhath Puja, amidst the spread of the coronavirus disease (COVID-19), in Kolkata, India on November 20, 2020. (Photo by Rupak De Chowdhuri/Reuters)

Veteran cholita wrestler Jennifer dos Caras, 45, holds a cement block over teen wrestler Lucero la Bonita in the ring in El Alto, Bolivia, Monday, January 21, 2019. Trainees of cholita wrestling are still a year away from their full professional debuts while competing in matches against established athletes. (Photo by Juan Karita/AP Photo)

Dancers from “LA Dance Project” perform, wearing a mask, during the drive-in show “Solo at Dusk” in Los Angeles, California, on October 13, 2020, amid the Coronavirus pandemic. (Photo by Valerie Macon/AFP Photo)

England supporters react at an outdoor screening in Hyde Park in central London as England lose the 2018 World Cup semi- final against Croatia in Moscow on July 11, 2018. (Photo by Simon Dawson/Reuters)

Poppy, a female Crowned sifaka, inspects a photographer's camera in the enclosure at the zoo of Mulhouse, eastern France, on March 5, 2019. The Crowned sifaka is a critically endangered species from Madagascar. (Photo by Sebastien Bozon/AFP Photo)

A woman wearing a kimono performs an uchimizu ritual outside a pachinko game parlor in Tokyo June 30, 2015. The splashing of water onto the hot asphalt in summer is an old Japanese tradition meant to cool down the air as the water evaporates. (Photo by Thomas Peter/Reuters)

Children play football in front of an abandoned train compartment next to a railway track in Dhaka, in this May 29, 2014 file photo. (Photo by Andrew Biraj/Reuters)