Port Isabel Police said four men bought $41,000 in gift cards at the Port Isabel Walmart.
They allegedly used fake credit cards they created themselves.
"They manufactured them themselves, said Port Isabel Police Chief Gualberto Gonzalez. They made copies of Visa, Mastercard cards."
Police said a tip led them to the suspects.
They said they worked with Immigration and Customs Enforcement as well as the Secret Service to arrest the men.
Police arrested 25-year-old Miguel Angel Ontiveros, 27-year-old, Juan Martin Medrano, 46-year-old Daniel Maldonado Garcia and 32-year-old Jose Hernan Zamora-Perez.
Police expect even more arrests.
"We do have information that they might have had| inside help from the store itself, said Gonzalez. Gonzalez said he thinks someone working at Walmart may have helped the men.
The suspects sit behind bars, their cars seized and filled with illegally purchased goods from Walmart and Ben's Liquor in Port Isabel.
Inside one car, police found over $1,300 worth of alcohol.
One box held over 30 bottles of Buchanan.
Two of the arrested men are said to be from McAllen.
The two others are said to be from Mexico.
Police said they think that's where some of the loot was headed.
"We expect that they're taking them into Mexico and selling it over there, because I mean they're not paying a penny for them, said Gonzalez.
Police searched a McAllen condo Thursday and a South Padre Island condo Friday.
They said they found more gift cards and more credit cards.
At this point police said only stores appear to be victims.
They said they are still investigating to find out if any of the credit cards involved were from real people.