GRINDSTONE, Pa. -- Officials are issuing a warning to pet owners after humane officers said dogs were killed as part of a satanic ritual in Fayette County.

Fire crews responded to a fire in the woods in Grindstone, Pa., on Thursday morning. What they found at the scene left the fire chief shaken.

Grindstone Fire Chief Rich Lenk told Channel 11 someone piled up a bunch of tires and lit them on fire. Above the burning tires were three dogs, including an 80-pound German shepherd mix, hanging from the trees.

Humane officers found satanic symbols near the fire.

Police are investigating and telling pet owners to keep a close eye on their pets, especially those who are kept outside.