Eight fire engines and 58 firefighters and officers have extinguished a blaze at a recycling plant at Ferry Lane in Rainham, east London.
A spokesman for Keeble Recycling said it was the firm affected but little damage had been done.
London Fire Brigade said all ducting between a paper shredder and baling machine and part of the mezzanine floor of an industrial unit were damaged. The cause of the fire is under investigation
Seven people left the property before fire crews arrived and there were no reports of any injuries.
The brigade said the fire was brought under control in just under four hours. Fire crews from Wennington, Barking, Dagenham and East Ham fire stations attended.