(WAND) – Hy-Vee said it is investigating a data breach involving payment card data at certain locations.

The company said in a statement its investigation into the breach involves transactions at some Hy-Vee fuel pumps, drive-thru coffee shops and restaurants. A timeline for when this breach occurred was unavailable in the release.

The locations believed to be involved include some Market Grille, Market Grille Express and Wahlburger locations. There is a Hy-Vee Market Grille location in Springfield, but it’s unclear what specific store locations had data taken.

“After recently detecting unauthorized activity on some of our payment processing systems, we immediately began an investigation with the help of leading cybersecurity firms,” Hy-Vee said. “We also notified federal law enforcement and the payment card networks. We believe the actions we have taken have stopped the unauthorized activity on our payment processing systems.”

Hy-Vee added it does not believe data in front-end checkout lanes, pharmacies, customers service counters, wine and spirits locations, floral departments, clinics and all over food service areas were affected, because those places have point-to-point encryption technology for card transactions that makes the data unreadable. Online transactions through Aisles Online are also believed to be exempt.

The company is reminding people to check card statements for any unauthorized activity and immediately let the financial institution that issued their card know about what happened.

“Because the investigation is in its earliest stages, we do not have any additional details to provide at this time. We will provide notification to our customers as we get further clarity about the specific time frames and locations that may have been involved,” Hy-Vee added.