Last Updated Aug 28, 2014 8:20 AM EDT
NEW YORK -- The FBI is investigating a hacking attack on JPMorgan Chase and at least one other bank, according to reports citing unnamed sources familiar with the matter.
These latest cyber attacks happened earlier this month and apparently were aimed at stealing checking and savings account information from a number of major U.S. banks including JP Morgan, CBS News correspondent Bob Orr reports.
Law enforcement sources tell Orr that the FBI and Secret Service now are working to determine the overall scope of the breach, which apparently involved a series coordinated attacks. It's not clear right now how much data may have been taken.
A report on Bloomberg.com said Wednesday that the FBI is investigating an incident in which Russian hackers attacked the U.S financial system earlier this month in possible retaliation against U.S. government-sponsored sanctions aimed at Russia.
The attack, Bloomberg said, led to the loss of sensitive data. Bloomberg cited security experts saying that the attack appeared "far beyond the capability of ordinary criminal hackers."
The New York Times, also citing people familiar with the matter, said JP Morgan and at least four other firms were hit this month by what it described as coordinated attacks that siphoned off huge amounts of data, including checking and savings account information.
While the targeted banks are not confirming these specific attacks, a spokesperson for JP Morgan told CBS News: "Companies of our size unfortunately experience cyberattacks nearly every day. We have multiple layers of defense to counteract any threats and constantly monitor fraud levels."
Sources tell Orr that so far, JP Morgan is not experiencing any unusual fraud activity.
The FBI declined to comment.
The Wall Street Journal also cited unnamed sources in a less detailed report that called the attacks a "significant breach of corporate computer security."
JP Morgan is the largest U.S. bank by assets.