Several horses and a cow were killed early Monday in a barn fire near the DeKalb/Clayton County line, authorities said.

Fire crews from both counties responded to the blaze, which broke out around 3:30 a.m. in a barn behind a home on Bouldercrest Road.

DeKalb fire Capt. Eric Jackson told The Atlanta Journal-Constitution that once firefighters knocked down the flames, they found the bodies of four horses and a cow.

“We don’t have any idea how the fire started or where it started,” Jackson said.

He said the fire destroyed the “extremely large” barn.