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)

Kurdish pesh merga troops fire at Islamic State positions as they move toward the Iraqi town of Badana Pichwk on Monday morning, October 17, 2016. Kurdish forces began Monday advancing on a string of villages east of Mosul, the start of a long-awaited campaign to reclaim Iraq's second-largest city from the Islamic State, which seized it more than two years ago, officials said. (Photo by Bryan Denton/The New York Times)

People wearing Christmas hats bath in a pool of watermelon peel during a Christmas service at a hot spring in Luoyang, Henan province, China, December 24, 2016. (Photo by Reuters/Stringer)

Alejandro Ccasa prays after waiting three days next to an empty oxygen tank for his uncle who has COVID-19 outside a refill shop where he is the first in line before it opens in Callao, Peru, early Tuesday, February 2, 2021. Ccasa said his family has one large tank and it gives about four hours of oxygen therapy. (Photo by Martin Mejia/AP Photo)

Photographer Mihaela Noroc travelled the world from Ethiopia to the US and from Guatemala to France in search of natural and authentic beauty. She introduces some of the inspiring women she met on her journey. Here: Ecuador. “More and more tribes of Amazonia are starting to adopt modern clothes for everyday life. But they are still keeping their traditional clothes for important events. I photographed this young woman in her wedding outfit”. (Photo by Mihaela Noroc/The Guardian)

People carrying torches march during the traditional Bonfire Celebrations in Lewes, Britain on November 4, 2017. Lewes holds Britain's largest Bonfire night celebrations. The event marks Guy Fawkes Night and the uncovering of the Gunpowder Plot in 1605 and commemorates the memory seventeen Protestant martyrs from the town who were burned at the stake. Thousands gather with flaming torches to march through the street and burn effigies. (Photo by Neil Hall/EPA/EFE)

Scottish Fold cat is displayed during a cat exhibition in Bishkek, Kyrgyzstan, 26 November 2017. Cats owners from Kyrgyzstan and Kazakhstan gathered in Bishkek to show their pets. (Photo by Igor Kovalenko/EPA/EFE/Rex Features/Shutterstock)

Members of p*ssy Riot perform in concert during Day For Night festival on December 16, 2017 in Houston, Texas. (Photo by Gary Miller/Getty Images)