Big online shoe seller Zappos.com is sending out a warning to its customers: we've been hacked and your information could be at risk.

FOX News Radio's Chris Foster has details:

Zappos.com customers - up to 24 million - are told their personal information may have been stolen: names, phone numbers, addresses, the last four credit card digits and passwords to the website (warned those should be changed immediately), in emails and a message on the company's website.

Zappos is based in Las Vegas, it's owned by Amazon.com.  Its CEO says a hacker broke into its system through a server in Kentucky.

Chris Foster, FOX News Radio.