NEW YORK (PIX11) — Sen. Kirsten Gillibrand is asking the Department of Justice and Treasury Department to help combat gun violence.

She wants the federal government to establish regulations for credit card companies to better track gun purchases, potentially preventing future mass shootings.

“The people who just max out their credit cards to do a mass shooting, we might be able to catch those,” Gillibrand said at a Sunday press conference.

She is specifically focused on ‘merchant category codes,’ which are four-digit numbers that credit card companies use to categorize businesses, separating book stores from department stores and fast-food chains.

Merchant category codes also track spending habits and help to spot fraud. Until recently, gun stores were categorized as ‘sporting goods stores’ or labeled as miscellaneous transactions.

“It’s been nearly impossible for banks to determine if a large, unusual charge on your credit card is for a set of golf clubs or for a gun,” said Gillibrand.

But, earlier this year, gun stores received their own merchant category code. Sen. Gillibrand says Visa, Mastercard and American Express are taking steps to implement it.

She now wants the DOJ and Treasury to issue guidelines so that financial institutions know how to report suspicious firearms purchases. Sen. Gillibrand says that better labeling gun purchases can also help catch traffickers, and could have flagged large purchases leading up to mass shootings.

“Before he carried out the deadliest mass shooting in modern history, the Las Vegas gunman spent $95,000 on firearm purchases, the bulk of which occurred in the year leading up to the shooting,” said Gillibrand.

Sen. Gillibrand also noted that the 2012 Aurora, CO shooter purchased $11,000 worth of guns, ammunition, and tactical gear on his Mastercard, and the 2016 Pulse nightclub shooter spent more than $26,000 on supplies using multiple credit cards.