COLLINS, Iowa -- The Sheriff's Office in Story County, Iowa, said Wednesday that nearly three dozen hogs were killed or injured over the weekend near Collins, Iowa.

Deputies and farmers said that what happened was not an accident, reported KCCI-TV in Des Moines, Iowa.

Finch said that sometime late Saturday night, gates were opened and more than 600 hogs were set free from the Struthers family farm northeast of Collins.

"When I drove up, there were pigs in the road. I mean, they were in a 20-acre radius around the buildings here," said owner Eric Finch. "Someone had been over here and purposely opened the gates."

He believes whoever set them free used their vehicle to chase the hogs through nearby farm fields, hitting and killing several of them.

"We did find strange tracks in the field behind and pieces of the vehicle," Finch said.

In all, more than 30 animals have been killed or euthanized because of the injuries they suffered, adding up to at least $3,000 in losses for the Struthers family.

"I think that the worst feeling I've had is when I had to pull the rifle out and come into my own building and shoot my own pigs, because of stupidity," Finch said.

Some of the animals that survived have broken and crushed bones.

"We're not making any money the way it is, and to have somebody come in and do this, just causes a bigger loss for us," Finch said. "Our hope here is that somebody will come forward and call the Sheriff's Department and lead to whoever is responsible because this is, in our opinion, this was blatant animal abuse."

Local businesses and farming groups worked with the Strutherses to assemble a $1,500 reward in the case. They don't want this to happen again.

Deputies are following up on some clues in the case, including parts of the vehicle that were found.