Chili’s Grill & Bar has informed customers of a “data incident,” saying some payment information was compromised at “certain” locations between March and April, and it will “continue to assess the scope of the incident.” The chain restaurant said it believes malware was used to collect credit and debit card numbers, along with cardholders’ names, from its payment systems.

“We deeply value our relationships with all of you and sincerely apologize to those who may have been affected,” the company said in a statement. “We take the security and privacy of your data seriously and are working diligently to address this issue.”

The company said it learned of the incident on May 11, but did not say which locations or how many customers were affected. The company said it is working with third-party forensic experts to understand the details of the incident.

“We are committed to sharing additional information on this ongoing investigation with our Guests as we learn more,” the company said, adding there was “no reason to believe” customers would be putting themselves at risk by using a credit or debit card at one of their locations, going forward.