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OKLAHOMA CITY – Less than a week after a popular fast food restaurant announced that it was the target of a data breach, a lawsuit was filed.

Officials with Sonic Drive-In, a fast food chain with nearly 3,600 locations, said this week they had been notified of “unusual activity” regarding credit and debit cards used at the fast food restaurant.

Sonic released a statement, saying:

“Our credit card processor informed us last week of unusual activity regarding credit cards used at SONIC. The security of our guests’ information is very important to SONIC. We are working to understand the nature and scope of this issue, as we know how important this is to our guests. We immediately engaged third-party forensic experts and law enforcement when we heard from our processor. While law enforcement limits the information we can share, we will communicate additional information as we are able.​”

At this time, the company does not know how many or which of its stores may have been impacted.

Now, a law firm has announced the filing of a lawsuit against Sonic regarding the data breach.

On Thursday, the law firm of Federman & Sherwood announced the filing of the first data breach lawsuit against Sonic Corp.

At this point, details of the lawsuit have not been released.