Somebody set up us the bomb.

The short version: someone managed to use an exploit to gain op powers, grant two other people with the same, they killed everyone else's access, then carried on to destroy Central and all areas with online players at the time.

We were able to stop the servers to prevent more damage from happening, close the loophole (discovered after a second griefing attempt some hours later), then restore everything that was damaged from backups. Since you weren't online for a few days, you wouldn't have noticed a thing!