The U.S. Secret Service and police in Hialeah and Homestead removed 13 illegal credit card skimmers during Operation Heat Check.

Federal agents and local police fanned out across Hialeah and Homestead to check gas pumps, ATMs and store checkout counters for hidden fraud devices, an effort that turned up 13 illegal credit card skimmers, the U.S. Secret Service said.

The operation, called Heat Check, paired Secret Service agents with the Hialeah and Homestead police departments. Investigators visited 378 businesses and inspected nearly 3,000 point-of-sale terminals, ATMs and gas pumps looking for devices that thieves attach to card readers to steal payment information. The Secret Service said the sweep prevented an estimated $13.5 million in fraud losses.

Surveillance video reviewed as part of the investigation showed how some of the devices got installed. In one instance, footage from inside a grocery store showed two people working together: one distracted a cashier while the other planted a skimmer on a card reader, the Secret Service said.

Skimmers are small devices, often just a thin overlay or an internal attachment, that capture card numbers and PIN codes when a customer swipes or inserts a card. Criminals can retrieve that data remotely or by physically collecting the device later, then use it to clone cards or drain bank accounts. Because the devices are built to blend in with legitimate card readers, they can go unnoticed by employees and customers for days or weeks before anyone realizes something is wrong.

Michael Townsend, special agent in charge of the U.S. Secret Service's Miami Field Office, said the operation was meant to catch skimmers before residents lose money, not after.

"Operation HEAT CHECK demonstrates that, alongside our local partners, the U.S. Secret Service is committed to identifying and pursuing those who prey on South Florida communities," Townsend said. "Our approach is proactive. Rather than waiting for consumers to become victims, we are working with businesses to help them recognize and report skimming devices before more people are impacted."

The Hialeah and Homestead sweep is part of a broader, ongoing Secret Service effort against payment card skimming, EBT benefit fraud and other financial crimes that has run in cities around the country. The agency has increasingly relied on direct inspection of retail and gas station equipment, rather than waiting for fraud reports or bank complaints, to find devices before they generate large losses.

The Secret Service said Miami-Dade County is a frequent target for skimming schemes because of its concentration of gas stations, grocery chains and tourist-facing businesses that process large volumes of card transactions each day. The agency said gas pumps are especially vulnerable because many stations still use older card readers that lack tamper-evident seals and chip-reading technology found in newer models.

The Secret Service did not say Wednesday whether arrests have been made in connection with the 13 devices recovered, or whether the grocery store incident captured on video is tied to any of the removed skimmers. The agency said the inspections themselves, rather than any single arrest, were the focus of the announcement.

The Secret Service said business owners in both cities should regularly check card readers and pumps for loose parts, unusual attachments or mismatched colors and textures that can signal tampering. The agency also advised customers to cover the keypad when entering a PIN, check for a matching serial number sticker on unlocked gas pumps, and use tap-to-pay or chip readers when available, since those methods are harder to compromise than a magnetic stripe swipe.

The Secret Service said it will continue working with police departments across Miami-Dade County on similar inspections, though no date has been set for the next round of checks in the area.