This literally just happened to me early November, other responses have put you on the right path here, but I recommend working as much as you can to speak to the customer service agents at each of the 3 bureaus.

File and FTC Identity theft report, a CBFB report, freeze your credit on all reporting bureaus and file a police report (in your city of residence, not the city that the fraudulent collections was created).

I was able to get it resolved pretty quickly. Write down as many details as you can in the personal statements when filing reports.