Twenty fire engines and around 125 firefighters were called to a fire on Hannah Close, Neasden.
Speaking from the scene, Assistant Commissioner Andy Pennick said: “The Brigade was called at 1136 to reports of a fire on Hannah Close, Neasden. Upon arrival, firefighters were met by a well-developed fire involving a waste transfer facility. Recognising the scale of the fire, the initial officer in attendance immediately requested twenty fire engines be mobilised to the scene.
"An industrial unit, approximately 100m by 150m was alight. At the height of the fire around 125 firefighters were in attendance. The fire produced a significant amount of smoke, with local residents advised to keep doors and windows closed.
"Four of the Brigade's 32m ladders were mobilised to the scene as part of our response, alongside the Brigade's Drone Team. A Hose Laying Unit and High Volume Pump were also deployed, increasing the amount of water available to firefighters as they worked to bring the fire under control.
"This is a protracted incident that will see crews on scene for the remainder of the day as they work to fully extinguish the fire. I’d like to thank our firefighters for their hard work so far at this fire, and our Control Officers for managing a significant number of calls and co-ordinating our response."
The Brigade's Control Room took the first of over 90 calls alerting them to the fire at 1134. Crews from Wembley, Park Royal, Willesden and surrounding fire stations were mobilised to the scene. The fire was under control by 1710.
The cause of the fire is under investigation.