We went through this a year ago after my husband's wallet was pickpocketed. If you haven't done so already, contact your bank's fraud unit and ask the people there if they recommend filing a police report as well; if they do, then do so ASAP. (The fraud unit at our bank required that.)
If you have not done so, immediately contact one of the three main credit bureaus -- Experian, TransUnion or Equifax -- and ask for a fraud alert to be put on your file. (Contacting one will trigger notifications to the other two.) The bank may also offer you free credit monitoring of your account for a year or so.
A section of the Federal Trade Commission website
is devoted to identity theft, listing the steps you need to take and the contact information for the credit bureaus. Be warned: There's a fair bit of paperwork involved in following all the recommended steps, but most of it can be done online through the links on the FTC Identity Theft site.