OAKDALE, Calif. (CBS13) — A therapy horse was killed after metal thieves tore down a pasture fence, allowing some of the animals to wander near a busy highway, authorities said.

An unknown number of suspects cut down a gate at the Daley Training and Learning Center, an organization that helps special needs children, allowing six horses to wander free, according to Laura Daley.

The horses traveled about a half mile from the pasture before reaching Highway 108, and all but one of the animals were able to cross the road safely. Calvin, a quarterhorse, was struck by a casino tour bus and died from his injuries. No passengers on the bus were harmed.

Daley said it would cost thousands of dollars to get another horse, but impossible to replace the good Calvin did for children. The stolen scrap metal likely only netted a couple hundred dollars for the suspects.

“He had such a good heart for the kids,” she said. “I’m angry at the blatant disregard of other people.”

Daley has set up a reward fund and online push to convince any witnesses to turn in the suspects.

“Some of the kids gave me their change, it made me cry,” she added. “The girl riding with me today did yard work, she pulled weeds to donate to Calvin’s fund.”