Vancouver-based Burgerville says thousands of customers’ credit and debit card information may have been compromised during a cyberattack.

Officials with the fast-food chain say anyone who used plastic to pay at its restaurants from September 2017 through last week should watch their card statements for unauthorized charges.

Burgerville said it learned of the breach from the FBI late in August although the chain didn’t acknowledge the issue until Wednesday. The company said its first priority was to contain the breach and close off cybercriminals’ access to its systems.

According to the company, the Burgerville attack was part of an effort to target American companies by a group based in Eastern Europe.

Burgerville has 47 restaurants in Oregon and Washington.