The fire started at a building at Martek Biosciences Corporation on Rolling Hills Drive in Winchester, near I-64, Tuesday morning.
Several crews were called to the scene beginning around 4:30 a.m., after a spray dryer, a machine that dries wet materials inside the factory, caught fire. The flames then spread to roofing material around a vent pipe, which spread the fire to the roof.
Fire crews had to cut a hole in the roof to access the fire and get it contained inside the dryer.
Winchester Fire Chief Daniel Castle says the sprinkler system went off but was shut off quickly to minimize the water damage.
Fire crews say they are familiar with the dryer fires at the factory, because it's an incident they've seen before.
They say it was a labor intensive operation.
One employee was inside when the fire broke, but no injuries were reported.
Castle says there is minor damage to the roof, but it shouldn't affect production at the factory.