The alarm was raised when flames were seen shooting into the sky at the pallet company on the Maesbury Road Industrial Estate at around 9.30pm yesterday.
Tim Davidson, watch manager at Oswestry Fire Station, said crews found the gate to the complex locked and needed specialist cutting equipment to gain access. An employee also arrived to help them get into the property and also assisted in moving pallets and logs to contain the fire.
About five tonnes of wood was destroyed but Mr Davison said: "Crews prevented a major incident by containing the blaze and saving thousands of tonnes of pallets and logs. Firefighters remained on site until after midnight."
The cause of the fire is being investigated but it is believed to have been accident.