As you may have noticed, there was a period of downtime, unfortunately on Sunday the server was compromised, however there is no evidence that any personal information was leaked, instead it appears that it was targeted solely for attacking other sites.
Fortunately, we detected it quickly and were able to take the site offline, take backups from before it happened and move them to a new, clean server.
I am going to continue checking the old server, which is locked down with no internet access to confirm the initial assessment.