The details have yet to be confirmed, but transactions in Forever 21 stores between March and October this year are thought to have been accessed.

American fashion retailer Forever 21 is this week dealing with the potential fallout of a major credit card breach at its retail stores.

In a press release, Forever 21 explained how a third party recently informed the company that there may have been unauthorized access to payment card data at a number of its retail stores. Right now, Forever 21 doesn’t know how far the breach extends, but an investigation is underway with the help of an unnamed “leading security and forensics firm.”

Although details of the breach are still unclear, Forever 21 is focusing in on card transactions that occurred between March and October this year. The breach also seems to be limited to stores that did not receive a 2015 encryption upgrade on their point of sale devices.

If you used a card to pay for goods in a Forever 21 store between March and October, Forever 21 asks that you monitor your card statements for signs of unauthorized charges. If you spot any, contact your bank or credit card company immediately.

Until more specific detail is released by Forever 21 it’s hard to pin down which retail locations are affected. Forever 21 operates hundreds of stores worldwide, with most of them located in the Americas, Asia, the Middle East, and the UK.

We will update this story as more information is released.