Firefighters are tackling a large fire at a car workshop.
The workshop fire on the A5 West Hendon Broadway, near Welsh Harp, has led to a huge emergency response this evening.
There are eight fire engines and around 60 firefighters at the site, alongside police, paramedics, and incident response teams.
The fire brigade says residents at nearby properties have been evacuated as a precaution.
There have been no reports of any injuries at this stage.
West Hendon Broadway is shut in both directions between Cool Oak Lane and Perryfield Lane.
The nearby M1 motorway was also shut in both directions between Staples Corner and Edgware from at least 9.15pm, with the flames visible from passing motorists.
The Thameslink railway line was also closed, but the track and M1 have both now reopened, the fire brigade said at 9.51pm.
There is still major congestion on the A5 between the North Circular and Station Road and motorists have been advised to avoid the area.
Significant clumps of smoke can be seen in the sky.
The London Fire Brigade were called at 6.42pm after receiving 44 999 calls and they are still at the scene.
Crews from Hendon, West Hampstead, Willesden, Mill Hill, Stanmore and Feltham are present.
MPS Barnet tweeted: "Officers are assisting our colleagues from @LondonFire at the scene of a fire on West Hendon Broadway.
"Road closures are in place and people are asked to avoid the area."
The London Ambulance Service said it sent an ambulance crew, hazardous response unit, and an incident response officer to the scene but have not treated anyone for any injuries.
The cause of the fire is not known at this stage, according to the brigade.
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