CANON CITY, Colo. -  

Federal officials are investigating the deaths of 19 horses at its Ca±on City Wild Horse Inmate Program facility, where Colorado inmates train select mustangs.

KOAA-TV reports the Bureau of Land Management found dead horses in a pen at the facility Monday, and several other wild horses in the pen were showing signs of illness. The BLM is working with veterinarians to investigate the cause of the illness, and the facility has been quarantined as a precaution.

Horses in the worst condition with a poor prognosis for recovery have been euthanized.

Necropsies on the dead horses are being conducted, and water and hay samples are being tested.