Blizzard has hotfixed a World of Warcraft exploit that allowed an unknown third party to kill all characters in some of the game’s major cities.

Both player characters and non-player characters in Stormwind, Orgrimmar, Tarren Mill, Ragnaros, Draenor, and Twisting Nether died instantly yesterday for no discernible reason.

Blizzard released the following statement via their official forum:

“Earlier today, certain realms were affected by an in-game exploit, resulting in the deaths of player characters and non-player characters in some of the major cities. This exploit has already been hotfixed, so it should not be repeatable. It's safe to continue playing and adventuring in major cities and elsewhere in Azeroth.

“As with any exploit, we are taking this disruptive action very seriously and conducting a thorough investigation. If you have information relating to this incident, please email hacks@blizzard.com. We apologize for the inconvenience some of you experienced as a result of this and appreciate your understanding.”