In the wake of the exploit being used, players and NPCs were all wiped from major cities in the game. The capital cities of Orgrimmar and Stormwind were filled with the bones of the dead after the exploit was executed. Once word started to spread, a number of realms were hit hard with this from those looking to cause a little trouble.
Fortunately, Blizzard was relatively quick to hotfix the issue. They also state that they are going to conduct a "thorough investigation" into the matter.
(via Battle.net forums, 2)