About 20 appliances are battling a large fire at Carter Holt Harvey's Kopine Mill near Thames.
Residents are reporting seeing large flames from as far away as Ngaruawahia.
A fire and emergency shift manager confirmed there were two large piles of wooden pallets on fire.
Crew from around the Waikato were in attendance to assist with water supply.
Fire crew were alerted to the fire at 9.20pm.