The Abaddon Hotel tragedy refers to a mass casualty event that occurred on the night of October 8–9, 2009 , at the abandoned Abaddon Hotel in Rockland County, New York. That night, a traveling haunted house attraction called Hell House was holding its opening weekend inside the hotel. At approximately 3:00 AM, a catastrophic incident resulted in the deaths of 15 people (guests and staff), with many others injured or permanently traumatized.