Thirteen bison from Yellowstone National Park were killed after being struck by a semi-truck, reports NBC Montana. The animals were apparently on or near a highway just outside the park—probably because of deep snow inside the park—when the truck hit them after dark on Wednesday, per the AP. Some of the bison were killed instantly and others were euthanized because of their injuries.
Police say two other vehicles were involved in the accident on US Highway 191, near the town of West Yellowstone, but only the semi hit the bison. “We are always saddened by any of these incidents, particularly when so many animals are lost," said a police statement. It adds that the animals' dark coloring and non-reflective eyes make them particularly hard for drivers to see at night. The accident is under investigation, and police say speed may not have been a factor. (Read more Yellowstone National Park stories.)