Originally Published: 29 JUN 22 10:55 ET

Updated: 29 JUN 22 15:07 ET

By Mark Morales and Pervaiz Shallwani, CNN

(CNN) -- Authorities in New York filed lawsuits against 10 companies selling parts for so-called ghost guns, in an effort to hold distributors accountable for the proliferation of mail-order components used to make untraceable guns that lead to shootings.

The lawsuits, invoking a newly enacted state "public nuisance" law, hit companies on multiple fronts, including one from the New York Attorney General Letitia James field against 10 distributors in state supreme court and another by the New York City Law Department against five of the same companies, filed in federal court in Manhattan.

The suit from the attorney general comes from an undercover investigation by state and city investigators, which determined tens of thousands of shipments to New York from addresses linked to the 10 business dating back to 2017, fueling what Mayor Adams said is "a city of mail-ordered murder."

As part of the investigation, undercover investigators "were able to purchase unfinished frames online from three distributors, who shipped them into New York without serial numbers or a background check," as required by law, the Attorney general's office said.

Using the weight and size of the packages, the attorney general's office said "it has reason to believe tens of thousands of shipments sent by the gun contain unfinished frames and receivers," in violation of local, state and federal laws prohibiting the sale of unfinished gun frames and receivers.

The city's lawsuit was filed in the US District Court in Manhattan following an undercover investigation by the NYC Sheriff's office. As part of the investigation, an undercover sheriff's office investigator at a Manhattan address used fake credit cards to purchase components and gun kits.

The city's law department said it is asking the court to immediately issue an order to stop the retailers from selling gun components in the city, while asking they provide addresses where guns and components have been mailed, said Sylvia Hinds-Radix, the city's Corporation Counsel, who is the city's top lawyer.

"With just a few clicks and a credit card, undercover investigators in the sheriff's office ... were able to order the components and use them to assemble guns that are illegal under city and state law," Mayor Eric Adams said. "These are dangerous weapons, we should not think these are just kits used for hobbyists — they're being used by murderers. All of them are illegal. Think about it: No matter where you live, no matter where you are, you can order one of these weapons and use it for whatever issues that you are attempting to resolve by using violence.

"We are not going to let gun companies turn New York into a city of mail-order murder. Whether they are hidden in the trunks of cars or in parks in a plain brown box, they are illegal and we will fight against it," Adams said. "We will take every lawful action possible to stop gun retailers from profiting over public safety."

The city is suing five retailers based in Missouri, Washington, Florida, and North Carolina. The retailers are:

Arm or Ally, based in Kansas City, Missouri;

Rainier Arms, based in North Auburn, Washington;

80P Builder, based in Largo, Florida;

Rock Slide USA, based in Broadway, North Carolina; and

Indie Guns, based in Orlando, Florida.

CNN has reached out for comment to the five retailers named in the city's lawsuit.

A lawyer for one, Florida-based Indie Guns, called the lawsuit a "politically-motivated effort to vilify a small business," in a statement, and said they expect to comment further after reviewing the allegations.

A person who answered the phone for another, North Carolina-based Rock Slide USA, said he had "no comment on the matter."

Governments act to crack down on ghost guns

The move by New York to hold accountable companies who ship the parts into its borders is the latest from state and federal officials around the country in an effort to curtail the proliferation of ghost guns. New York is the latest to join in filing a lawsuit. Los Angeles has sued a major manufacturer of guns and has called on credit card companies to stop processing the transaction of the guns.

The growth of ghost guns, which still make up a small number of the overall number of guns in the country, has raised concerns because of the rate at which the problem is growing and because the guns are nearly impossible to be identified.

The number of untraceable ghost guns recovered at city crime scenes or seized through investigations has increased about 200% each year since 2018, when the first such weapons were discovered in the city, one official said.

As of June 14, the city has recovered 175 ghost guns, compared to 64 ghost guns through the same period last year, a second official said. In all, the NYPD recovered 270 ghost guns last year.

A CNN analysis earlier this year of 2021 data found while ghost guns still make up a relatively small percentage of the total number of guns recovered by law enforcement, several cities reported sharp increases in the number of ghost guns recovered over time. San Francisco police told CNN they seized 1,089 guns in 2021, about 20% of which were ghost guns. In 2016, ghost guns made up less than 1% of total gun seizures in the city.

In a report released last month, the ATF determined between 2016 and 2021, more than 45,000 firearms suspected of being privately made, including ghost guns, were recovered by law enforcement from potential crime scenes and reported to the ATF. Nearly 20,000 of those firearms were recovered and traced in 2021 alone.

In April, President Joe Biden announced new requirements for ghost guns, including background checks before a ghost gun can be purchased and requiring serial numbers be included on some components.