Authorities nationwide are issuing a warning about the gift card scam called card draining as many holiday shoppers look to buy gift cards as Christmas gifts.

They are warning those that have purchased or plan on purchasing gift cards from retailers to exercise caution and look out for any signs of tampering, such as scuff marks or scratches near the bar code on the back of the card.

A California man was arrested for tampering with gift cards at a Target store in Sacramento last week, the Sacramento County Sheriff's Office said.

Police say Ningning Sun was found with more than 5,000 gift cards from Target and Apple in his possession.

The sheriff's office said their investigation revealed that Sun was part of a gift card scam spanning across California and several other regions nationwide.

"Victims are completely unaware it is happening, and the money is often siphoned to an off-shore account within seconds," said the sheriff's office.

"These operations are very sophisticated and modifications to the gift cards are often virtually undetectable, even to the trained eye," the sheriff's office said.

The sheriff's office has also suggested avoiding buying gift cards altogether.

The New Britain Township Police Department in Bucks County, Pennsylvania, also issued a public notice on Dec. 1 about the card draining scam.

According to the notice, police were investigating two reports of gift card tampering involving over 100 Visa Vanilla and Apple gift cards at Giant locations in Bucks County.

New Britain Township police advise customers to check all gift card packages for tampering.

"If a gift card is suspected to have been tampered with or opened, do not buy it and bring it to the store manager or service desk," the notice says.

Gift card tampering:Man arrested after Target gift cards tampered with in California, shoppers warned

How does the card draining scam work?

According to the Sacramento County Sheriff's Office, the card draining scam involves tampering with bar code on gift cards and stealing the money loaded on them.

The Sacramento's Sheriff's office said that Sun was seen acting suspiciously near the gift cards in the payment aisles in a Sacramento Target store before his arrest.

"Detectives observed him placing all the gift cards on a rack inside his jacket, then replacing the gift cards with another set of seemingly identical ones," said the sheriff's office. Sun was confronted while trying to exit the store with the stolen gift cards.

The Pinole Police Department in Pinole, California, said in an Instagram video that the scheme involves the scammers removing gift cards from sealed envelopes and slicing away the code that the recipient needs to activate the card.

How to protect yourself from the gift card scam card draining

According to the Pennsylvania Attorney General's Office, here's how to protect yourself from this scam:

• Make sure the gift card is sealed and the protective cover and the tape covering the pin is intact
• Ensure the gift card does not appear to be tampered with
• Keep the store receipt in case the gift card you are purchasing is found to have been compromised
• If a purchased gift card is found to be compromised, immediately report it to the gift card company directly, to request a freeze on the card, and request a refund.

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