67 horses have died from an "unknown and highly contagious disease at a Colorado facility

A federal wild horse facility about 100 miles south of Denver has gone under quarantine after 67 horses died from an "unknown yet highly contagious and sometimes fatal disease," reports CNN.

The horses started getting sick on April 23. Veterinarians are trying to diagnose and treat the horses. T

The Director of the American Wild HorseCampaignn, Suzanne Roy, says the horses' deaths are a "direct result of the Bureau of Land Management's inhumane mass roundups."