MSNBC has an article on this new phenomenon.
I was a victim 3 weeks ago and Facebook security were totally useless. As the article notes there's no phone number to contact Facebook directly so you're left filling out contacts forms. I sent half-a-dozen over the course of the first 3 days, the hacker was still using my account over a week later. It took 2 weeks for Facebook to even contact me about the issue.
The scam that the article describes is exactly the same one that I fell victim to - the messages, tactics, everything.