MSN is reporting that AMEX has been hacked, and user financial information is at risk

Account numbers, names and other credit card information such as the expiration date of 'some customers' have been compromised.

It is also reported that letters to AMEX customers say, 'It is important to note that American Express-owned or controlled systems were not compromised by this incident, and we are providing this notice to you as a precautionary measure.'

MSN elaborates by saying, Gerilyn Cammaroto, vice president of American Express's communications, told DailyMail.com: 'This incident was not caused by a data breach at American Express or at a service provider of American Express. ... [It] resulted from a point of sale attack at a merchant processor in which American Express Card member data was impacted.