More than 200,000 Anthem Blue Cross customers this week received letters informing them that their personal information might have been accessed during a security breach of the company's website.

Only customers who had pending insurance applications in the system are being contacted because information was viewed through an on-line tool that allows users to track the status of their applications.

Cathy Luckett of San Juan Capistrano was dismayed to learn that Social Security and credit card numbers were potentially viewed.

"I'm thinking this is the 21st century," said Luckett, 57, who bought an individual policy in February. "I expect this company, Anthem Blue Cross, to protect my information."

The information was briefly accessed, mainly by lawyers looking for information for a class action lawsuit against the company, an Anthem spokeswoman told the Orange County Register.

The insurer doesn't know how many records were viewed, but letters were sent to 230,000 Californians as a precautionary measure. Attackers would have been able to get the information by manipulating URLs, a security breach open for a relatively short time. A third-party vendor validated that security measures were all in place, but in fact they were not, the company said. Anthem says it closed the security hole immediately.