Firefighters from several stations got the call of a possible fire in Goulds shortly before 9 p.m. Monday.
Firefighters from Mount Pearl were first on the scene. They reported seeing flames and heavy smoke from the Robert E. Howlett Highway long before reaching the scene.
Neighbours, including other farmers in the area, raced to the scene as well and were successful in rescuing about two dozen cows.
There were about 120 cows in the barn at the time of the fire.
Firefighters were hampered by the lack of water in the area. Water had to be trucked to the scene.
The Back Line road remains closed. There is no word on the cause of the fire.