Hey. The same thing happened to me about a year ago and again this past Thursday. I live in Colorado and called the police station. They have a department dedicated to this kind of fraud.
It's worth it to give your local police station a call and report it. The more people that call and report it will increase the likihod of the scammers being caught
Good Luck
The caller states they are with the IRS and that I'm being sued for back taxes. This is a scam since I know that the IRS would send out an official notice.