(RNN) - Michaels Stores Inc. has released information that gives specific details about the data security breach that affected 3 million of its customers.
A 45-page document lists stores affected and dates when payment cards were compromised at each location.
The company said it hired two independent security firms to conduct an extensive investigation after it learned about the security hack in January.
The company narrowed down the timeframe of the breach to between May 8, 2013 and Jan. 27 and said the number of cards compromised represented about 7 percent of transactions during that period.
"There is no evidence that other customer personal information, such as name, address or PIN was at risk in connection with this issue," Michaels said in a statement.
By comparison, a Target cyber security breach discovered in late 2013 affected about 110 million customers.
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