A 1,200-pound Quarter Horse died over the weekend after falling into a sinkhole in Queen Creek, Ariz. An Associated Press story on KVOA.com reported Sunday (July 22) that the 11-year-old horse, Cash, “became trapped last night when it fell into a large fissure that opened up” at a residence.

After Cash fell into the fissure–which is estimated to be a quarter mile long, ten feet wide in some places, and at least six feet deep–he began to sink in “heavy, sticky, claylike mud,” according to Humane Society representatives.

During the horse’s rescue, he died suddenly and unexpectedly. Veterinarians attributed the death to exhaustion or a possible catastrophic injury that caused internal bleeding