Neiman Marcus and Target Corp may not have been the only retailers to be the target of severe hacks this holiday shopping season.

According to a report in Reuters, data breaches of at least three other smaller retailers took place. Reuters cites anonymous sources familiar with the matter, and received a “no comment” from the Secret Service.

Reuters doesn’t provide any concrete information about these smaller retailers who may have been hacked, only that they have stores in malls.

It’s not clear whether these hackers are the same group behind the previous attacks. Reuters reports that “similar techniques” were used as the hack on Target.

Yesterday, we reported that the Target breach may have affected up to 70 million people. Last month, Target divulged that hackers bypassed its security systems between Nov. 27 and Dec. 15, stealing information for 40 million debit and credit cards. The retailer didn’t indicate that personal details on tens of millions of other customers were also compromised.

Target thieves not only gained access to credit card numbers but also to three-digit CVV security codes, which merchants aren’t supposed to store. Scam artists can use that information to make purchases at retail stores.

Merchants like Target are required to report breaches of consumer’s personal information. The Secret Service and Department of Justice are investigating the Target breach.

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