If you've used a credit or debit card to make a purchase at a Target store since Black Friday, read this!

The Secret Service has been brought in to investigate as Target says that up to 40 million card accounts may have been affected by a data breach. Anyone who used a credit or debit card to complete a purchase since Black Friday is at risk. Investigators believe that information was hacked from the magnetic strips on cards as they were swiped through Target's red card readers. More details in the video below.

The Federal Trade Commission offers these suggestions on how to tell if you have been a victim of identity theft;

Request a copy of your credit report.

Watch your mail carefully, and look especially for offers or statements from cards that you don't already have.

Check your statements or log into your accounts to look for charges that you didn't make.

If you think that you may be a victim of identity theft, immediately place a fraud alert on your cards, order a credit report and file an identity theft report.

Target Corp. also invites customers who may have had their credit information hacked to call 866-852-8680.

More good information on identity theft from the Federal Trade Commission can be found here.