People in part of north-west London are being told to keep their doors and windows closed as fire crews deal with a major blaze in an air conditioning workshop.
Eight fire engines and 58 firefighters are at the scene of the blaze at a single storey air conditioning workshop and offices on Headstone Road in Harrow, north west London.
Crews believe an acetylene cylinder is involved and a 75 metre hazard zone has been put in place as a precaution.
The cylinders are prone to exploding when exposed to heat.
Police are helping to evacuate properties in the immediate vicinity of the blaze.
A London Fire Brigade spokesman said: “The fire is producing a lot of smoke in the local area so we would advise people living and working nearby to keep their doors and windows closed as a precaution.”
The incident was reported just after 3pm, and at this stage the cause of the fire is unknown.