The Garden Grove Police Department arrested two men who were installing a credit card skimming device on a bank ATM last week, and now police are warning the public to look out for signs that a credit card reader may be compromised by thieves.

The two suspected skimmer operators, 22-year-old transient Remus Virtan and 55-year-old Los Angeles resident Ion Ionita, were arrested on Sept. 22 after they were caught installing a skimmer at a Bank of America in the 13900 block of Brookhurst Street, Sgt. Willie Holloway told KTLA.

They face charges of grand theft and attempted theft using a skimming device, and police are investigating if they are connected to any other such incidents.

After the men were seen installing the devices by an ATM monitoring service, police were alerted, and after the men were detained, a detective who is “familiar with the devices” returned to the ATM and found the skimmer, Holloway said.

What that detective found was a Bluetooth skimmer in the card slot, as well as a disguised camera and SD card to record users’ PINs as they accessed the ATM, Holloway said.

Police offered several tips for keeping your finances safe from card skimmers, which Holloway noted can be “hard to spot as they are often inserted into the card reader.”

“If the card does not insert smoothly or gets stuck while ejecting, this could indicate a skimmer is in use,” Holloway said in an email. “Additionally, people should look for items such as small cameras concealed around the ATM that could record their activity. ATM surveillance cameras are obvious by intent, however skimmer cameras will be externally affixed and harder to spot.”

To protect yourself from cameras, use one hand to cover the other while you enter your PIN.

Also of concern: “shoulder surfing,” or someone looking over your shoulder, as well as cameras with audio capability that will record your PIN if you were to say it out loud.