Story highlights Chick-fil-A says the possible breach happened at a "few restaurants"

The chain did not specify which restaurants or their locations

Chick-fil-A said it first learned of suspicious payment card activity on December 19

Chick-fil-A is working with law enforcement to look into potential unusual activity involving card payments at a few of its locations, the fast-food chain said.

The chain did not detail the extent of the possible breach, the number of restaurants or the locations.

The company learned on December 19 that there was "limited suspicious" payment card activity "appearing to originate from payment cards used at a few of our restaurants," it said in a news release Wednesday.

"We take our obligation to protect customer information seriously, and we are working with leading IT security firms, law enforcement and our payment industry contacts to determine all of the facts."

Chick-fil-A said it will let customers know more details later, and it added that if a breach is substantiated, customers will not be liable for fraudulent charges. The company also said it will pay for identity protection services to those affected, including credit monitoring.

Anyone concerned about payment card transactions should call 1-855-398-6439.