ALBANY, N.Y. (WWLP) — New York’s Attorney General, Letitia James, joined a coalition of 18 other attorneys general to call on their federal counterpart, Merrick Garland, to close what they call the ghost gun loophole.

“There is only one purpose for the sale of deadly ghost guns — to put guns into the hands of those who are legally prohibited from owning a firearm,” James said in a statement. “The proliferation of these types of weapons has not only caused indescribable suffering across the country, but gravely endangers every New Yorker. Ghost guns put dangerous weapons into the hands of terrorists, criminals, and domestic abusers, which is why we are calling on Attorney General Garland to close the loophole in the Gun Control Act and prohibit the sale of 80 percent-complete receivers to those who are already banned from purchasing weapons. This is about protecting our schools, our offices, and our places of worship from turning into killing fields.”

The loophole stems from the way the U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) interprets the federal Gun Control Act, allowing criminals, domestic abusers, and other prohibited purchasers of firearms to evade federal gun laws to purchase “80% receivers.” They can be easily assembled into unserialized and untraceable ghost guns.

Ghost guns are privately made firearms without serial numbers, making them untraceable by law enforcement. Ghost guns often start as 80 percent receivers that are frequently sold in kits without background checks. James and the other attorney generals—including Maura Healey of Massachusetts and T.J. Donovan of Vermont—say the ATF’s interpretation is incorrect. They say 80% receiver kits sold online and at gun shows throughout the country without background checks violates common sense.

The attorneys general released a letter to Garland on Monday. In it, they push him to issue a new interpretation of the Gun Control Act. They say 80% of receivers should be included in the category of firearms that require background checks.

“Ghost guns pose a serious threat to public safety—they’re untraceable and are often made from easily obtained household items, allowing people to circumvent our laws,” said Healey of Massachusetts. “My office has been working with our federal, state and local law enforcement partners to get these guns, which are increasingly used in crimes, out of our communities. We’re calling on the Attorney General of the United States to make clear that these guns require background checks, so we can protect our residents from these dangerous weapons. The time to act is now.”

The metal or plastic “lower receiver” is where the actual “firing” of the bullet comes from. Although the lower receiver is subject to federal regulation, if it’s incomplete—lacking certain holes, slots, or cavities—it can evade federal regulations.

Joining James, Healey, and Donovan on the letter are the attorneys general of Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Iowa, Michigan, New Jersey, New Mexico, North Carolina, Oregon, Pennsylvania, Rhode Island, Virginia, and Washington.

Take a look at the letter sent to Garland: