LAS VEGAS (KLAS) — A virus is being blamed for the deaths of 95 wild horses since Saturday at a Colorado facility, according to a Bureau of Land Management news release.

The horses died over the course of five days — April 23-25 — at the facility in Canon City, Colorado. A total of 2,184 horses are kept at the facility, which is attached to a corrections unit about 115 miles south of Denver.

Lab tests have identified an equine influenza virus as the likely cause of the deaths, part of a respiratory disease outbreak.

About 10% to 20% of the horses at the facility have been affected with more mild influenza symptoms.

But a group of horses taken in an emergency roundup in 2021 after a wildfire has seen more severe effects. Those horses were part of the “West Douglas” roundup.

A quarantine has been put into place, with no horses allowed to leave until officials determine the animals are healthy and there is no larger threat to domestic horses in the community.

“The Bureau of Land Management will review operations at the Canon City facility to prevent future outbreaks like this from occurring,” said BLM Colorado Acting Associate State Director Ben Gruber.

“This tragic outcome was influenced by a population of horses that may have been particularly vulnerable given their time in the West Douglas area and their exposure to last year’s wildfire that prompted their emergency gather,” Gruber said.

Officials said the equine influenza outbreak is not related to an influenza outbreak that is affecting wild bird populations.