A large fire in Colindale that brought a motorway to a standstill is believed to be accidental.
London Fire Brigade believes the fire at a range of car workshops in West Hendon Broadway was caused by combustibles being stored too close to a heat source.
Eight fire engines were called to the fire on October 7, which saw the whole of the single storey units destroyed.
Firefighters cooled three cylinders to an ambient temperature as some cylinders can explode when exposed to heat.
As a precaution, around fifty residents were evacuated from nearby properties.
There was major congestion on the A5 between the North Circular and Station Road and the M1 was temporarily closed between junctions 1 and 4.
The fire was under control by 10.30pm.