BILLINGS, Mont. (AP) — More than 50 Yellowstone National Park bison have escaped through a cut fence at a containment area where they were being prepared for transfer to the Fort Peck Tribes.

Fifty-two of the animals escaped from two pens at the Stephens Creek facility near Gardiner on Tuesday, and the National Park Service has begun a criminal investigation.

The bison had been in containment for nearly two years to assure they were free of brucellosis, a disease that can cause livestock to miscarry.

Interior Secretary Ryan Zinke called the release devastating and said it's unclear if the bison will have to be quarantined again or if they can still be considered a minimal risk for brucellosis.

It appears that someone cut the fence with bolt cutters.

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