(NBC News) Damage control is in full swing at retail giant Target as millions of customers scramble to find out if they are victims of one of the largest data security breaches in history.
An estimated 40 million debit and credit card numbers, along with PIN numbers and other customer info, were stolen over a span of 19 days.
Thieves accessed Target's terminals, and stole what's called "track data" from the cards - numbers, names, security codes, expiration dates.
Target is now issuing a letter to customers, apologizing and saying they're working with a forensics firm to find the culprits.
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