Also I think you should probably shut the site down or at least halt gambling, give yourself some time to do a full data audit, code review, whatever you need to do to.
Wow, this escalated much faster than I thought. Lucky gambler takes 120+ BTC, chat is closed, and of course no indication on the website of what was or is going on. I hope that sig campain members will remove their signatures. It would be irresponsible to feed more traffic into the site at this time.