BOZEMAN – Yellowstone National Park officials said rangers arrested two people who were trying to chain themselves to a corral where wild bison are held.

Park spokeswoman Vicki Regula said rangers arrested the two people Tuesday afternoon. She declined to identify them or say whether they were being detained or charged.

The Bozeman Daily Chronicle reported the people arrested are affiliated with an advocacy group called Wild Buffalo Defense and seek to draw attention to the slaughter of bison.

The corrals are where bison are held when they are captured leaving the park. Some are shipped to slaughter to reduce the herd’s size and over concerns of disease spread.

Bison escaped from the corrals in January and February after intruders cut through fences.