Los Angeles County District Attorney George Gascón and law enforcement officials called on three major credit card companies Tuesday to stop accepting online payments for the purchase of ghost gun kits.

Ghost guns are sold mostly on the internet for between $350 to $500 and can be assembled at home into a working firearm. They are called ghost guns because they have no serial numbers, are unregistered and are therefore untraceable by law enforcement.

The firearms can be purchased without background checks, allowing those who would be legally disqualified due to a felony, domestic violence conviction, mental illness or being underage, to easily purchase a kit, according to a release from the DA’s Office.

“American Express, Mastercard and Visa have the ability to go beyond what any law enforcement agency, legislature or city council can accomplish,” Gascón stated.

Gascón was joined by Los Angeles Police Chief Michel Moore and San Gabriel Police Chief Gene Harris in urging the companies to halt online transactions involving the guns.

“We are asking these companies to join us in stemming the flow of ghost guns into our communities by preventing a ghost gun kit from being sold with a few mere clicks on a smartphone or computer,” Gascón stated.

Since 2017, the number of ghost guns seized by the Los Angeles Police Department has increased by approximately 400%, according to the DA’s release.

Last August, LAPD reported that ghost guns accounted for 33% of all guns it recovered in suspected criminal activity.

Gascón says that by banding together as they did in 2015 to stop payments on backpage.com, which was accused of facilitating sex trafficking, credit card companies can take meaningful steps to improve public safety.