More than 900 chickens at a California farm were beaten to death with a golf club last month, The Los Angeles Times reported Tuesday.

The gruesome scene was discovered Sept. 20 at the Foster Farms chicken shed in Fresno. Authorities believe at least one person broke into the farm and slaughtered 920 chickens.

"Whoever did something like this is pretty sick," Deputy Chris Curtis told the paper. "It would take a long time to do it…People should be alarmed at something like that."

Police believe the intruder or intruders gained entry to the farm after bending back the protective fence. The farm is offering a $5,000 reward for any information leading to an arrest.