Over 6 fire crews between Clearfield and Centre County battled a fire at Walker Lumber Company late Wednesday night into Thursday morning.
Crews were called in just before 9:30 Wednesday night.
Between Wednesday night and Thursday morning around 100 first responders were at the lumber yard at different times.
Three employees at the lumber business were in the building and escaped safely.
There were two different mayday situations when the roof partially collapsed from the fire.
Two firefighters were treated for the first partial roof collapse and the second roof collapse caused two other firefighters to be taken to the hospital with non-life threatening injuries.
The fire Marshall came to the scene to investigate the cause of the fire. Crews are expected to stay on scene throughout the morning.
The Salvation Army from Clearfield County came to provide food, drinks, emotional and spiritual support to the firefighters.