I agree with SPLASH and Robmack.
If any data was taken including dumps of hashed passwords you should be making a community announcement and forcing password changes. If the data was taken you should assume thats its already been compromised. You would not believe the amount of people that use the same password for their primary email that will then be linked to things like Banking, Netflix, Facebook, PayPal, ebay etc. If they got the email address and its the same one you use to pay pal they then have Half the required credentials to access your paypal. If they have your email and your password is the same as the captured one they can then easily access your Paypal by hijacking the email. So its really important to let us know what was taken via an announcement. By not doing you actually may be opening yourself up to liability issues.
Good luck working with the security to get the stuff locked down. If you need a private security guy to step in Im sure I and others on the forum can recommend you some people. (Probably some users are in this feild)