New York Attorney General Letitia James and California Attorney General Rob Bonta sent a letter to three major credit card companies Friday urging them to create a specific category for all gun and ammunition sales.

James and Bonta wrote MasterCard, Visa and American Express asking for a new merchant category code to flag any suspicious activity for law enforcement agencies, including large firearm or ammo purchases. The category code could help police prevent gun violence and reduce the risk of illegal gun trafficking, according to the letter.

“Credit card companies categorize purchases on nearly everything from groceries to gas to clothing, but no category exists for the multi-billion-dollar gun and ammunition industry,” Attorney General James said in a statement. “Categorizing gun sales can help us work with our partners in police departments to combat gun violence and save lives. This is a common-sense solution that credit card companies can implement to help keep New Yorkers, and all Americans, safer.”

Most purchases made by credit card are labeled with a four-digit merchant category code, but none exist for firearm sales, according to the attorneys general. Several people who carried out mass shootings in recent years bought their weapons with a credit card.

Credit card companies use merchant category codes to flag potential money laundering or terrorism.

“We must use every tool in our toolbox to combat the deadly threat of gun violence,” AG Bonta said in a statement. “That means everyone in this country, including credit card companies, has an important part to play in our fight to save lives and combat senseless violence. Today, two of the largest states, with two of the strongest firearms safety laws, are standing together to call on credit card companies to create a spending category that would help law enforcement better identify terrorism and gun trafficking. This has never been more urgent — people are dying from gun violence each and every day. Preventing gun violence is on everyone: from law enforcement to business leaders to community members.”

Gun violence kills more than 40,000 Americans annually and is the leading cause of death for children and teens, according to James' office.

Representatives from the credit card companies' registration and management groups evaluate and vote on new merchant categories. Merchant category codes must be separate from all industries that have a code, and the minimum annual sales and volume of merchants included in the category must be at least $10 million to be considered, according to the attorney general's office.