The barn fire that killed more than 500 animals in Prince William County, Virginia, has been ruled an accident, although fire officials say the barn was so badly damaged that they can’t tell what the exact cause was.

The fire started around 3:30 a.m. Sunday in Gainesville, along Lee Highway. About 500 chickens and ducks, four dogs and three pigs died in the fire. No humans were hurt.

“Due to the severity of the destruction, an actual fire cause cannot be determined,” fire officials said in a statement Monday.

They said the barn was privately rented, and was not part of a commercial operation.