Authorities are investigating the deaths of more than 300,000 chickens at South Carolina farms that supply chickens to Greeley-based Pilgrim’s Pride Corp. (Nasdaq: PPC), according to media reports.

People with knowledge of raising chickens may have killed the birds following layoffs of about 60 people at Pilgrim’s Pride, Clarendon County, S.C., Sheriff Randy Garrett told Reuters. The 325,000 chickens killed in the past two weeks were worth about $1.7 million.

Garrett did not return a message left with the Clarendon County Sheriff’s Office, which is seeking the killers.

Vandals adjusted temperature levels in chicken houses, killing young birds and older ones alike, Reuters reported.

“These unfortunate, yet apparently deliberate acts show a blatant disregard for the welfare of the chickens and the livelihood of the family farmers involved,” a company spokesman said in an email statement. “We are fully cooperating with local authorities.”

Pilgrim’s Pride shares fell 3 percent to $27.20 on Thursday.

The company contracts with more than 4,000 family farmers in the U.S. and Mexico to grow chickens for its processing operations. Pilgrim’s Pride provides the birds, feed, and technical and veterinary services, while growers provide the labor, housing, litter, utilities and chicken-raising expertise.