BOISE, Idaho (AP) — Idaho wildlife officials say an attack by two wolves panicked a flock of sheep and 143 died after they ran into a gully where they were crushed and suffocated.

The Idaho Department of Fish and Game and the U.S. Department of Agriculture’s Wildlife Services on Thursday confirmed the sheep deaths in mid-May in southwestern Idaho in foothills north of Boise.

The area is popular for recreation such as mountain biking and hiking, and also has deer, elk and large predators such as bears, mountain lions and wolves.

Sheep owner Frank Shirts says it’s the worst incident of wolf predation he’s experienced since wolves were released into central Idaho in 1995.