Company representatives said the hacking happened sometime between August and September. Dairy Queen executives said they are working with law enforcement and credit card companies to investigate.

>> Complete list of affected restaurants

So far, there is no evidence that Social Security numbers, personal identification numbers or emails were stolen.

International Dairy Queen Inc. has about 4,500 franchised stores in the U.S. It's also the parent of the Orange Julius chain, and one stand-alone Orange Julius store was breached.

The Edina, Minnesota-based company, which is owned by Warren Buffett's Berkshire Hathaway Inc., is offering customers free identity repair services.

—The Associated Press contributed to this report

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