Police Call Scam

We got a call today. The caller ID said 'Washington DC'. I'm not sure if the area code was really for Washington DC or not, but I couldn't check then. It was from a woman with a thick accent claiming to be with the police. She said there was a crime and we were responsible for it. She gave a case number and said that if we, or our attorney, don't call back, then she can only wish us luck as this all unfolds on us. I panicked after that, trying to think of what it could be. But as I calmed down, I started thinking about it. If there really was a crime we could be arrested for, the police wouldn't call. They'd come to our door. And they wouldn't just 'wish us luck as this all unfolds on us'. They wouldn't say that. She said that was all she could do if we didn't call back. Not to mention that she never said what this supposed crime was. I think it was a scam. But it really worries me. I'm trying not to panic. 
                                                                     ~The Blogging Fangirl