13 bison were killed in a three vehicle wreck in Yellowstone National Park on Wednesday night. 

The accident happened on December 28th at about 6:30 p.m. near mile marker 4 on U.S. Highway 191 near West Yellowstone, Montana. 

According to Cowboy State Daily, the crash involved one semi truck and two passenger vehicles crashing into a herd, killing 13 bison. No people were injured in the incident. The stretch of roadway was plowed, but covered in packed snow and ice.

Some bison were killed instantly while others had to be euthanized. Marty Zaluski, Montana State Veterinarian, says that he’s never heard of such a crash killing that many bison. Zaluski says that bison often stick to roadways when it snows because travel is more efficient. 

“If they want to get from point A to point B, they recognize that the road is the most efficient,” he said. “With the recent snowfall, they haven’t got well established trails they’ve gotten beat in quite yet.”