Now to a breaking CONSUMER ALERT - for anyone who shopped at Target within the last few weeks - including Black Friday. You'll want to be on the lookout for fraudulent charges on your credit and debit cards. Less than an hour ago - Target confirmed up to 40 million credit card accounts may have been affected by a data breach. Channel 4's Erica Rakow is looking into this - she joins us LIVE with important information ... 3 3 TARGET SAYS THE BREACH MAY HAVE STARTED THE DAY BEFORE THANKSGIVING - AND WENT ON THROUGH THIS PAST SUNDAY. IT IMMEDIATELY ALERTED THE AUTHORITIES AND BANKS. AND NOW - MILLIONS OF CUSTOMERS ARE BEING WARNED TO CHECK THEIR ACCOUNTS. 3 00-0510-15TARGET SHOPPERS ACROSS THE COUNTRY AREN'T LEAVING THE STORES WITH A WARM FEELING AFTER HEARING ABOUT A POSSIBLE SECURITY BREACH."It's scary...I'm curious has to how that happened in the first place. "EXPERTS BELIEVE HACKERS BROKE INTO TARGET'S COMPUTER NETWORK, STEALING DATA COLLECTED WHEN CUSTOMERS SWIPE THE MAGNETIC STRIP ON THE BACK OF THEIR DEBIT AND CREDIT CARDS."It lets them take that information and encode it onto a new card and essentially duplicate that card and use it as if it were their credit card at any store."COMPUTER SECURITY EXPERT BRIAN KREBS BROKE THE STORY AND SAYS DATA WAS STOLEN FROM BLACK FRIDAY, A HEAVY SHOPPING DAY, UNTIL THIS PAST SUNDAY.IT DID NOT AFFECT ONLINE SALES AT TARGET.IT'S UNKNOWN IF DEBIT CARD PIN NUMBERS WERE BREACHED WHICH WOULD ALLOW CROOKS TO DRAIN CASH DIRECTLY FROM ATM'S. HOWEVER IT COULD TAKE MONTHS FOR TARGET SHOPPERS TO LEARN IF THEY ARE VICTIMS, SO YOU HAVE TO PAY ATTENTION TO YOUR STATEMENT."You can as a cardholder are not liable for these charges but there's a catch. You have to report it. You have to say I didn't make these transactions and if you're not paying attention to your statement you may miss that."SOME SHOPPERS ARE THINKING TWICE ABOUT USING PLASTIC."Probably cash now. I do have cash for what I need tonight." 3 AMERICAN EXPRESS AND DISCOVER SAY THEY'RE BOTH AWARE OF THE INCIDENT - AND HAVE FRAUD CONTROLS IN PLACE. IF YOU SUSPECT FRAUDULENT CHARGES ARE ON YOUR ACCOUNT - CALL TARGET AT 1-866-852-8680. THAT NUMBER IS POSTED ON OUR FACEBOOK AND TWITTER PAGES.