Updated: 12/19/2013 5:38 AM
Created: 12/18/2013 5:24 PM KSTP.com
By: Jennie Olson
The Secret Service is investigating a data breach regarding credit card numbers at Minneapolis-based retailer Target Corporation.
Target is reportedly looking into the theft of millions of in-store credit card and debit card records from its databases, according to KrebsOnSecurity. Target says up to 40 million card accounts may have been affected by data breach.
Customers all over the United States were victimized, the report said. It may have been the result of software installed at the machines customers use to swipe their cards when paying for their purchases, a person familiar with the situation told The Wall Street Journal.
The breach reportedly started on or around Black Friday, Nov. 29, one of the busiest shopping days of the year. It could have extended to at least Dec. 6, and possibly as long as Dec. 15, according to the report.
Online customers apparently have not been affected by the breach, according to the report.
Key factors in the breach such as what kind of information was targeted has not yet been revealed, according to the report.
KSTP's request for comment by Target was not immediately returned.
Target has 1,797 stores in the U.S. and 124 in Canada.
Guests who suspect unauthorized activity should contact Target at: 866-852-8680.
The Associated Press contributed to this report.